Tuesday, April 26, 2016
Protect transistors from AC oscillation spike using diode 1N4007
Converting DC to AC using transistors circuit is commonly available on Google but the real application could be a headache for beginners. AC oscillation in reverse direction could easily damage a transistor in a matter of seconds. Some people out there recommended using capacitors to keep the current ripple stable which i have yet to try. But anyway i have tested using diode to prevent reverse oscillation definitely works.
In this circuit experiment turning 9 volts to 570 volts AC with the addition of voltage multipliers circuit. 3 transistors were damage in the process namely 2 x TIP41C + BD139 - I thought it was cause by heat but after putting in heat sink and also using thermal paste didn't stop the transistors from getting fried. Therefore the heat was not really the problem in the first place.
But anyway now using BD139 with the diode 1N4007 is placed between the transistor collector and the transformer it works so far so good.
One simple circuit to step up voltage using LM2577 -Adj P+ chip. The schematic is from Texas Instrument and it works expected - and below is...