Showing posts with label Electronics. Show all posts
Showing posts with label Electronics. Show all posts

Sunday, March 31, 2019

Simple 4G LTE signal booster / amplifier that finally works

The components are purchased cheaply and yet the circuit is also very simple. This is my first prototype 4G LTE indoor signal booster that I am currently building to solve the slow internet connection that I've experience for so long.

In the past 9 years streamyx internet connection has been doing unfair capped bandwidth at 2 Mbps and yet the reality performing only around 0.5 Mbps ~ 1 Mbps and the connection keeps on turning on and off. Then I go for DiGi 4G LTE 100 GB internet package that comes with the HuaWei WiFi mobile modem - it's doing alright with signal strength around 1 to 2 bar performing at 3 Mbps and below. I guess anyone out there using Digi Internet experiencing almost the same day in day out. I am pretty sure of that unless your house is located next to the Cell Tower station.

Based on the android signal software analysis the DiGi could actually provide up to 72 Mbps super fast connection but that's probably if the device is placed right on the cell tower microwave antenna which is not going to happen. In reality we will get around 1 Mbps ~ 3 Mbps and sometimes 5 Mbps depending on the proximity between the device (mobile phone) to the cell tower distance. That speed usually linger around -107 dBm to -101 dBm which is below average. This happens usually when you are inside the house.

Signal Strength Analysis based on LTE discovery android software:

-107 dBm to -101 dBm = 1 Bar
-99 dBm to -90 dBm = 2 Bar
- 89 dBm to 80 dBm = 3 Bar
- 70 dBm and below full bar

Which means the higher the negative value the weaker is the signal strength otherwise the lower the negative value is the stronger the signal strength.

Having said all that I've made quite sometimes of research to build antenna amplifier / booster for the HuaWei modem to get better signal that it is currently receiving. And here comes the final prototype running on 20 Mhz crystal to modulate the weaker signal into 20 Mhz output.

The following are the components:

20 Mhz Crystal Oscillators
Coupled Inductor 20 mH
Air core inductor 2.5 Turns
2 x Input antennas (to harvest signal from surrounding environment)
1 x Output signal to transmit / broadcast the signal to the HuaWei modem

Despite the circuit output only 20 Mhz but there is quite significant impact of it to the HuaWei Modem signal - as you can see in the video demonstration it could amplify up to 4 bars signal which increase the internet speed within 9 Mbps to 15 Mbps range. And the signal strength is very consistent as oppose to without the amplifier circuit.

NOTE: When signal is very weak within your area - the modem signal strength sensitivity becomes very high which means a slight movement and placement (angle) of the modem could effect the signal strength significantly. That's why if you found a good spot and position where the signal is very strong take note of it because the rest of other positions / placement could be very bad. In this circuit do not place the transmitting antenna too close to the modem because the signal output will over powered the modem input signal. Placing too far is also not good because the signal cannot reach the modem. In my case i purchased special made 4G LTE antenna with two coil on the antenna and placed it within 7 cm away from the modem. This is the best distance that i have experimented. I believe different antenna could possibly emitting different signal strength - so self experimentation is required how far it is from the modem.

To ensure your circuit works - test using a multimeter with the Hertz mode. The crystal should transmit / oscillate around 8 Mhz ~ 12 Mhz at the output and the ground of the crystal should generate around 2 Mhz ~ 4 Mhz. If anything lower than this it could affect the signal strength - please experiment at your own discretion. Connect only the output connection to the output antenna and do not connect the ground because it will provide a constant frequency 20 Mhz. A constant frequency is not good and you must allow it to oscillate to emit the RF signal.

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Simple Easy 3.7 Volts DC to 3000 Volts AC - Power Moseft IRFZ48N

A simple circuit to convert 3.7 Volt DC battery to 3000 Volts AC using fast switching power mosfet IRFZ48N. The transformer is salvaged from faulty power supply with center tap primary. The component is very simple and easy to put together

The DC to AC circuit

1 x 1000 Ohm Resistor
1 x IRFZ48N Power Mosfet
1 x Mini step up transformer with center tap primary

The Voltage Multiplier to amplify the voltage up to 3000 volts

8 x Ceramic layer capacitors that can withstand up to 3 kilo Volts (3kV) of voltage and 8 diodes 1N4007 diodes. This is the simple schema if you have any question just let me know

10 Nano Farads Ceramic Capacitor or 0.001 Micro Farad is good enough

Simple RF Mobile Signal Detector Schematic Diagram Circuit to detect VHF/UHF 4G LTE

Very cool RF mobile signal detector from simpletronic - the circuit is main driven by high frequency RF transistor up to 6 Ghz maximum. It can easily detect low frequency and high frequency electromagnetic and RF signal. In this demonstration using a smart mobile phone using 4G LTE (2600 Mhz / 2.5 Ghz Frequency) and when the internet is running the signal will be captured as a result the LED lights up. Another test is done on an antenna that transmitting 20 Mhz signal and it lights up brightly because the power used is 5 Volt to amplify the 4G modem.

Component of the mobile signal detector circuit

100 Ohm, 10 KOhm, 47 KOhm - Resistors
10 KOhm - Variable Resistor
BFG591 (UHF 6 Ghz Frequency RF Transistor)
Blue LED
10 pF - Ceramic Capacitor
10 Cm - Antenna
CR2032 (3 Volt) Battery

Circuit Schematic Diagram

How to detect 4G signal | 4G signal detector | Mobile Signal Detector Circuit |

4G Signal booster / amplifier circuit using LM386

This is just an experiment to test if it is possible to amplify / boost 4G signal for the HuaWei-E5577 modem so that i can enjoy decent internet speed consistently. The circuit is very simple driven by LM386 amplifier IC and two antenna. One is the receiver antenna another the transmitter antenna powered by 5 Volt USB PC usb power supply.

The complete component is as follow

1 x project box for casing
1 x 4700 uF Electrolyte capacitor
1 x 1000 uF Electrolyte capacitor
2 x 4.7K Resistors
2 x Antennas with SMA male connectors
1 x USB female port
2 x SMA female connectors

The output of the result is very interesting - although there is no sign of signal indicator increase on the Huawei-E5577 modem but the internet connection looks faster than usual and it is very consistent. Despite of having 1 bar 4G signal the internet still capable of loading YouTube videos very smoothly and serve the internet normally. 

I understand that this amplifier is not capable of delivering 4G signal but the RF amplification via the LM386 seems to have effect on the HuaWei-E5577 modem. Noted that the amplification doesn't seem to work on normal smart phone device. Not sure what exactly the cause.

Anyway now i can enjoy consistent internet speed that have been poor for the past 9 years. It's different this time.

NOTE: Some people may not believe this works - but please take be reminded i do not post something that doesn't work. And at the very least it works for me.

4G Amplifier / booster circuit schematic diagram

Simple 4 Volt DC to 400 Volt AC output circuit using mini step up transformer

Simplest DC to AC inverter circuit using 2 Phase primary 1 phase secondary mini step-up transformer powered by TIP41C NPN transistor. This circuit can step up 4 Volt DC to 400 Volt AC

Cheap 4G LTE booster / amplifier circuit - weBoost

This is the second version of the 4G LTE booster that I've made - an improved version of the first design 4G Booster. Instead of using antenna to transmit the signal to the modem as in the previous designed the second version using SMA to TS6 coaxial connector cable to directly connect to the modem internal antenna.

The new designed is much more efficient and there is no longer the need to put the antenna at certain distance to transmit the signal to 4G modem. And instead direct connect into the modem antenna making the signal 80% efficient with 80% stability.


1 x 4G Antenna (Input Antenna)
1 x Coupled Inductor 20 mH
1 x 20 Mhz Crystal
3 x 2.5 turns air core inductors
2 x 7.5 turns air core inductors
1 x SMA to TS9 splitter coaxial cable output direct to Modem
Powered by 5 Volt USB

During the day when the 4G traffic are congested due to heavy usage by many active users the signal will fluctuate within the range 3 ~ 4 bars. In the night the signal consistency is much higher especially after 12 midnight as less people are using their phones the signal will stays around 4 bars with 70% consistency.

The construction of this circuit is very cheap probably under $10 USD and you can find the component easily available on eBay. However keep in mind that the crystal oscillator - please get a genuine one from well known manufacturers or from store such DigiKey, Element14, Mouser, RS-Online. I have learned my lesson those crystal made in China is not going to work and in fact you will get around 80% faulty or the frequency precision is not stable.

The reason is very simple with genuine Crystal Oscillator the signal precision is much more efficient and this will keep the stability of the signal produced.

NOTE: There are plenty of 4G signal booster out there made in China but they will work temporarily or not work at all. There are also the one working made in the USA like weBoost, Verizon, T&T booster but they are all expensive.

There is something that I've learned researching on the Microwave UHF signal and the device which capture it like the HuaWei modem. The modem can hold a memory of signal - which means when it goes low and then idle, there is likely the modem will continuously holding low signal until you restart the modem then it will refresh. This behavior maybe vary from one device to another so I can't tell of different devices signal patterns. This memory holding issue can be resolved by restarting the PC and the modem so that fresh signal amplification can reset itself.

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Saturday, March 30, 2019

How the mosquito racket / bug zapper / fly swatter high voltage generator works.

One of the simplest electronic components that most people overlook is the mosquito racket or most commonly called (bug zapper or the fly swatter). The circuit is very simple consist of 3 major parts as follows.

The charger parts: 1, 2, 3, 4, 5, 6

The DC to AC inverter parts: 8, 9, 10, 11, 12, 13

Voltage Multiplier parts: 15, 16, 17, 18, 19, 20, 21

We are going to replicate how the circuit works using only the necessary components as follows:

No.11: NEC D882P NPN Transistor
No.12: 650 Ohm Resistor
No.13: High voltage mini-transformer (6 pins)

And all the voltage multiplier components

3 High voltage diode rectifier RFC4K
221K 4KV Capacitor (220 pF)
CBB81 223J2KV (0.022 uF 2KV Metallized Film)
2 x Unknown capacitor which i believe it is around 2KV to 4KV

The re-assembly of the circuit will be as look like the schematic diagram as shown below

Below is the video demonstration step by step how to re-assemble the circuit. Note that the circuit output is not as efficient as the original because of the loose connection on the breadboard. It would be much more efficient if it is soldered permanently.

Many people have underestimated this bug zapper and it actually the most use components on YouTube videos to make high voltage circuits. The most important part of the circuit is the mini-high voltage transformer which is difficult to find if not because of the fly swatter device. Apart from that there are high voltage ceramic mylar capacitors which can be reused for another projects such as DIY voltage multiplier, Tesla coil circuit, taser (stun gun), etc.

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Simple doorbell circuit using 555 timer + schematic diagram included

A very simple doorbell circuit driven by 555 timer chip. This kit you can find it cheap on eBay less than $1 - but if you are the type who can't wait like me and having the components available why not just build one. So the components are not exactly the same but it works almost exactly the same.

1 x 555 timer IC
1 x momentary switch
4 x 47k resistors
2 x 4148 diode
1 x 10 uf electrolytic capacitor
3 x 103 ceramic capacitor
1 x 8 Ohm speaker
100 uf Capacitor

Friday, March 29, 2019

Easy Simple 12 volt DC Battery to 220 volt AC inverter circuit

A simple conversion from 12 DC Battery to 220 AC inverter circuit schematic diagram.


1. Transformer (230 V) - with primary center tap
2. 12 Volt Lead Acid Battery
3. UF4007 Diode (Can be replace with 1N4007 Diode)
4. 4.7 KOhms Resistor @ 1 Watt
5. 1 Micro Farad @ 400 Volt Metalized film capacitor
6. 06N03LA NPN Transistor (This can be any NPN Transistor or N-Channel Mosfet)

12 Volt DC to 220 Volt AC Inverter Circuit Diagram | Convert DC to AC circuit diagram|

Thursday, March 28, 2019

LM386 amplifier circuit schematic diagram complete 99.9% noise removal from ground loop

For those who are new to the LM386 IC may stumbled to a point facing all sort of noise related problem when using it to make an amplifier circuit just like me. It can be very challenging to avoid the sensitive noise and in fact the ground signal from our body contact also can cause significant distortion to the sound output of the circuit. You can try this just by putting your hand or touching one of the circuit component that is not grounded - the distortion noise is very obvious.

There are many videos on YouTube from some experience and experts showing how to avoid the ground loop noise from the Lm386 circuit by correctly connecting all the ground connection. Indeed this has very significant improvement that we should take note how to connect the ground to avoid noise.

However this solution is not enough to completely remove the ground noise - and when you put your ears close to the speaker you can still significant listen to the screeching / crackling noise in the output even if there is no sound to amplify. Indeed it is very annoying and frustrating for some at least to me. Especially earphone / headphone the noise is very obvious since it is placed right on the ears - the noise is not very pleasant to hear.

So after making some research i discovered the perfect solution to avoid the ground noise. And two of this component place at the input and the output would ultimately remove the noise. When there is no sound to amplify there is 100% clean no noise at all completely quiet. The two component are a mini transformer place at the input (step down mode) and a coupled inductor place at the output.

The circuit schematic is look like this. Now for the first time you can use the LM386 circuit to make a mini earphone / headphone amplifier without worrying about the distorted crackling and screeching noise. This is for real 100% working circuit as per prototype shown in the video!

Real physical schematic diagram LM386 noise cancel (remover)

Easy simple stereo amplifier circuit using TEA2025B IC - powered by 5 Volt USB

A very simple stereo amplifier circuit using TEA2025B IC chip powered by 5 volt USB. The component is quite are not very complicated just some electrolyte capacitors and ceramic capacitors as well as potentiometer. The sound is extremely loud - I am pretty sure further research to improve the circuit will produce good sound especially the bass.

The schematic is shown as below.

How to make audio 5 Volt diy guitar stereo guitar amp on breadboard

Very cheap and simple guitar audio amplifier using the TEA2025B. You can get $0.99 for 10 unit of the TEA2025B IC on where i got mine. This is my prototype demonstration on a breadboard and it turns out not bad. The output sound is pretty decent for a small sub-speaker.

The clarity of the sound is obviously better than the recommended LM386 IC that people use for a small guitar amp DIY that i've found in Google. Dual speaker in the video is just a demonstration and it is possible to make a mono output using a different setup of the circuit schematic. For the time being i will stick to this until further improvement in the future. I would like to make this for real for myself so that i can fine tune the distortion and tone control. 

There will be improvement in the future for this circuit possibly with the addition of pre-amp circuit to allow controlling the tone and also alter the sound clarity.

TEA2025B IC How it works?

The IC internal structure actually builds based on 2 separate amplifiers circuit combined and that's why it can generate stereo output sound. Refer to the diagram below as you can see pin 9 to 15 is the first amplifier with an input, ground, and output. Pin 2 to 7 is the second amplifier circuit. If you observe closely over and over again the circuitry in the IC actually very simple.

Pin 16 is positive power source comes in.

The stereo version of the circuit optimizes both input on pin 10 (first amplifier) and 7 (second amplifier) and the output separately out on pin 15 and 2 respectively. The component required is pretty simple and common.

2 x 0.22uF Ceramic capacitor
2 x 0.15uF Ceramic capacitors
2 x 470uF Electrolyte capacitors
2 x 10k potentiometer / variable resistors at the input
6 x 100uF electrolyte capacitors
2 x speakers

The internal structure of the TEA202B is as shown below.

The mono version of the amplifier only utilizes the first amplifier input on pin 10. While the second amplifier input is connected to the ground. The component in the TEA2025B mono amplifier is as follow:

0.22uF Ceramic capacitor
2 x 0.15uF Ceramic capacitors
10kOhm resistor - reduce noise
6 x 100uF electrolyte capacitors

The advantage of TEA2025B is the power it uses is very small from 5 volts up to 15 volts as per datasheet. Even at 5 Volt the circuit is already sound quite loud and that gives the advantage of instead using batteries that will drain out juice we can use 5 Volt USB power from computers and mobile chargers.

TEA2025B Noise

Just like the LM386 the TEA2025B is very sensitive to ground noise - and there is all sort of noise coming from the surrounding environment including from strong RF frequency and floors. You can test this just put your hand closer to the circuit the noise becoming worst.

Secondly, if you are using USB power supply there is also noise coming from the AC to DC conversion. That small electromagnetic fields disturbance could really affect the amplifier sound.

How to handle the noise is to use a resistor - this you can experiment for example you can try 370 Ohm at the input signal connected to the ground. Secondly, a resistor with the same value connects between the negative power source to the ground pin of the IC. This will reduce noise significantly and if you want it to be perfect you have to experiment on your circuit which one resistor value suit the best.

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Home made DIY - How to make auto scan radio on breadboard

This is my first homemade DIY auto scan radio. Yes -- usually small radio is based on analog with the coil antenna which is difficult to wind to a specific band. This radio circuit only depends on one central microchip BK1079 and in fact, this is just a prototype and it works quite well on a breadboard.

The Good auto-scan radio.

It does not require specific antenna winding like the analog radio - which reduces the experimental job on the antenna. It depends on the processing frequency within the microchip as long as the radio signal is within reach it can detect all the FM frequencies in range just with the push of seeking button.

Component Required for building the Auto-scan radio

1 x BK1079 radio chip
1 x 100 nH - inductor
1 x 18 pF ceramic capacitor
1 x 100 nF ceramic capacitor
1 x 10 uF electrolyte capacitor
3 x 10 kOhm resistors
3 x push button (reset, seek, and volume)
1 x antenna (simple)
2 x AA Batteries (3 volt DC)

How to make

Step 1: Convert BK1079 SMD to use Through Hole pin using MSOP-10 board adapter

Firstly I am working on through board/breadboard and the BK1079 is an SMD (surface mount device) mount. We need an adapter board which converts the BK1079 to use for through-hole board purposes with pin package MSOP-10. In this case, I don't have MSOP-10 but I can still use alternative board MSOP-16 which has more pins.

The soldering process requires some experience since the pin are very tiny and close to one another. One thing you have to avoid is the bridging join during soldering.

Step 2: The components assembly

The assembly on breadboard seems to be easy since it is just plugged into the holes. However, bear in mind that anything to do with frequency transmission requires a very solid connection. So you don't want any loose connection otherwise the radio signal will fail or too much noise later on. Find breadboard cable jumper that snug fit into the board holes. This is to prevent noise or failed frequency signal.

Then assemble the component based on this simple schematic diagram below.

Realistic circuit diagram Auto scan radio

auto scan radio circuit

The antenna is optional - because it does not bring so much different to signal received based on my experiment. The microchip is so special that it can receive signal quite clear even without an antenna but perhaps just get one or a piece of wire as antenna just to make sure everything are in place. However if you have germanium diode as the antenna that would be the best because it can capture all range of radio frequencies from MF (Medium Frequency), HF (High Frequency), VHF (Very High Frequency), and UHF (Ultra High Frequency) which means from normal radio signals up to ultra-high mobile phone signal such as 4G LTE.

It is advisable to solder the push button on permanent circuit board because putting it on the breadboard would be too shaky and it will fail the circuit. So by soldering on permanent board, it's placement is rock solid.

Step 3: Testing the output

Try not to use higher voltage to avoid burning the circuit - so use the specified voltage using 2 AA batteries (3 volts). Secondly, try to get the speaker a little longer cable so that you can put a little bit further than the circuit during testing. Because if you the speaker is too close it could disrupt the signal and produce great noise than usual. Good luck with your project.

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How to cancel / terminate TM streamyx internet

It has been 6 years ups and downs with TM streamyx but the recently instability in the connection is completely unacceptable. The internet connection is on and off every 1 or 2 minutes and it happens almost everyday. In the past it wasn't so bad at least take few hours but this time it's totally unusable.

I fully understand the TM always recommend to call their support but that will helps only a while and the problem will come back again sooner or later. I know this for the past 6 years so - it's a kind of standard problem. It's time to stop paying RM130 a month for 2 Mbps connection which in actual usually around 1 Mbps or less or most of the time cut off frequently.

Probably this is the cause of shared internet connection - once the residential users increases especially the heavy internet users then someone else going to suffer for it. So i will solve this once and for all at least for now and never again. Until TM improve the connection and service significantly - one thing for sure is no point to provide internet and let the users pay for it but it is totally unusable. It stops a lot of thing especially in term of work and entertainment.

By the way I've made some reading across few forums and there are plenty of complaints by other people about their streamyx connection problem. So i guess i am not the only one having this problem. It would be good if there are new internet service provider to fill in this gap left by TM i guess a lot of people will migrate their internet connection instantly. Like in matter of weeks.

So here is how it was done

1. Go to nearest TM point (in my case UTC Taman Kereta Kuching)
2. Inform the officer you want to terminate the streamyx service
3. They will ask for reasons - my case is simple bad connection
4. Identity Card (IC)
5. Fill in the cancellation / termination service form as below

How long does it need to disconnect? As stated in the document it takes at least 14 days (2 weeks) for the Streamyx termination process to be completed.

Berapa lama streamyx pembatalan? 14 hari (2 minggu) | Borang pembatalan perkhidmatan internet TM streamyx | Potong streamyx

Wednesday, March 27, 2019

DC to DC boost converter step up 4 volt to 12 volt LM2577

Another good demonstration of the LM2577 boost converter IC to upgrade mini-portable fan power. The original circuit of the fast is quite slow and the speed runs as if it was using the battery directly. Since i still need this fan to keep away soldering smokes so i decided to use the LM2577 IC to upgrade the power from 4 volts to 12 volts DC. It turns out to be a perfect upgrade - now i can use my USB 5 Volt port to power up this fan instead of the battery to avoid recharging it over and over again. I have tried a few IC before for example using 555 timer + mosfet and also the Linear Technology LT1172 but the result is not turn as i expected. Although the voltage is upgrade but the amperage output is not satisfactory compare to the LM2577. Apart from that the simplicity of the circuit and also the regulated voltage output is really perfect a small voltage step up.

Simplest 4G Signal Internet Booster / Amplifier - 20 Mhz Active Crystal Oscillator

One of the project I am working on is to improve 4G internet signal and this is just a preliminary test using a simple 1 component 20 Mhz active crystal oscillator powered by 5 Volt USB charger. The surrounding area I live is well covered within the 4G signal but due to the HuaWei modem is placed in the room there are so many obstacle stand in the way causing the poor 4G signal reception. So i thought making a booster / amplifier would help get a better signal.

From the observation of the experiment it is indeed seems to work - even at 10 Mhz the oscillator have effect to the 4G signal reception to the HuaWei Modem. The normal signal without the booster averaged around 1 ~ 2 bar and the speed fluctuate within 2 Mbps or less. Using the active crystal oscillator 20 Mhz amplifier the signal bar is consistently at 3 bar and even if it falls to 2 bar the signal is above the normal 2 bar. The internet speed fluctuate within 7 Mpbs and 15 Mbps - occasionally it would rise up to 25 Mbps when when the signal bar is 5 but that happens not so frequency.

However at the very least 3 bar is good enough to stream - smooth YouTube videos and also surf the internet with blazing speed and smooth. The ultimate goal of the project is to achieve 2600 Mhz or 2.6 Ghz to achieve the same frequency as 4G and by that time i hope it will get full 5 bar and the internet will be consistent speed is at 25 Mbps.

To assist with the signal distribution I have made a new external antenna from cut soft drink can. It's very simple and easy to do so I don't have to explain that but - if you intend to do just make you have to sand paper where you would like to connect the crystal oscillator frequency output. It is because all soft drink can are insulated with a thin coated later of plastic or pain that prevent electrical signal to flow.

The result of the test is very satisfying although it may not get the full 4G signal but the internet speed perform above average and it really helps my internet for good since then. I am very very glad of this simple RF amplifier.

Tuesday, March 26, 2019

High step up current joule thief circuit - powered up multiple array of 8 volts LED using 1.5 AA battery

The conventional Joule Thief usually using the 2N2222A NPN transistor which amplify current to power up LEDs ranging with minimum input voltage at 600 mV. However the brightness of the LEDs are not so significant compare to the high current transistor such as TIP41C as shown in this video. As you can see multiple arrays of LEDs bulb that requires at least 8 volt each can be light up simultaneously using 1.5 AA battery at once. This is provide more current then the smaller 2N2222A transistor.

Cheap Chinese made batteries has found its place in this circuit - and you don't need to buy expensive branded batteries anymore. And perhaps you can make your own batteries using aluminum + carbon and power up LEDs using this circuit. It gives an idea what we can do when we are living in remote area where electricity is not available - just with 1 piece of AA battery you can have a good lighting or probably making flashlight out of it.

12 Mhz crystal oscillator / resonator circuit to amplify RF signal (4G)

This is an experiment to obtain high frequency signal using the Crystal oscillator / resonator. - The idea is to get high frequency to amplify RF signal and multiply that signal using frequency multiplier (coming soon) to achieve 2600 Mhz or 2.6 Ghz signal and this will help to amplify the 4G mobile signal. This intention arise from the frustratingly weak 4G signal around my area despite the cell tower are everywhere coming from different directions and based on the signal map area - it is well covered within moderately strong 4G signal but unfortunately the signal reception i get is lesser than it should. So this is an initial pilot project to achieve the higher frequency to amplify 4G signal that coming from the antenna. The circuit will have 1 input antenna place outdoor to receive the 4G signal then amplify in the circuit and finally to the indoor antenna like a repeater device.

There are 4G booster / amplifier / repeater out there made in China but it cost quite a price. Having said that the experiment only cost few cents of component probably less than 1 buck. So I am going to make this happen sooner or later to solve my 4G signal. For the record if full 4G signal strength is obtain the internet speed provided by the DiGi service provider could go up to a maximum of 25 Mbps which is almost lightning speed fast and quick. Currently i get around 1 Mbps or less.

Circuit 1: To generate 12 Mhz frequency

1. 12 Mhz Crystal Oscillator
2. 1 Kohm Resistor
3. 10 Kohm Resistor
4. 1100 Kohm Resistor
5. 680 Kohm Resistor
6. 150 pF ceramic capacitor
7. 68 pF ceramic capacitor
8. BC547 BJT NPN Transistor

Easy Simple Flies Swatter / Mosquito Swatter Racket / Bug Zapper 100% working schematic diagram

This is an easy simple flies swatter / mosquito swatter racket / bug zapper 100% working schematic diagram. To make it easy for the electronic enthusiast out there to understand and learn how it works. Basically it consist of the following electronic components.

1. High voltage step up boost mini-transformer (2 Primary and 1 High voltage secondary)
2. NEC D882P (NPN Transistor)
3. 3 High voltage diode rectifier RFC4K
4. 221K 4KV Capacitor (220 pF)
5. CBB81 223J2KV (0.022 uF 2KV Metallized Film)
6. 2 x Unknown capacitor which i believe it is around 2KV to 4KV

Note: The High voltage diode is quite rare and it's quite costly because it rated 2000 to 3000 volt / 0.2 and it's a fast recovery rectifier diode. Refer to the RFC4K diode datasheet.


·fast switching
·Low leakage
·high current capability
·high surge capability
·High reliability

Note: The transformer is has 2 primary (green and orange as indicated in the diagram) and 1 secondary (red). At 3 DC volts the transformer can amplify voltage up to 500+ volts AC. Then it is amplify again using the voltage multiplier to produce few thousands volt spark to kill mosquitoes, flies, bugs, etc.

The idea of learning this bug zapper is because there is more things that we can modify from it and turn it into high voltage and make something else out of it. I.e. Stun Gun / Taser, Electromagnetic pulse device, and perhaps ionizer. I am pretty sure someone out there have more hidden ideas that can be done from this zapper. It also provides an idea how DC can be turned into AC easily and many more ideas can pop up out of this swatter if you learn in detail. The overall component if purchased separately is very costly - you would rather buy the zapper itself and salvage its component instead which is way much cheaper.

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How to light up 24 LEDs using 1 x AA battery 1.42 volt - The most powerful joule thief circuit

This is one of the most efficient Joule thief circuit capable of powering up 24 LEDs using a single AA battery at 1.4 volts. The components are very simple and cost less than 2 dollars to make except for the breadboard.

4 x 82uH inductors
2 x 1N4007 Diodes
1 x 5.6KOhms resistors
2 x 10nF ceramic capacitors
1 x Breadboard

The maximum voltage for the circuit is around 3 volts to 3.5 volts - anything more than that could fried the transistors. I have yet to test the minimum voltage to power up the 24 LEDs and if this can goes to the lowest minimum like 700 mV then it can be powered up using normal chemical reaction such as Vinegar, Lemon, etc.

This is the illustrated schematic - click to enlarge

After soldered on permanent circuit board - it's a small circuit as big as thumb finger.