Help! Need advice choosing proper resistor value.

Discussion in 'Power Electronics' started by Rahulk70, Feb 14, 2017.

  1. Rahulk70

    Thread Starter Member

    Dec 16, 2016
    Hi guys, I made a simple inverter circuit for a neon lamp using the parts I salvaged from an old power ATX PC Power supply. So, I had two 13007-H2 NPN transistors and the power transformer from the ATX supply and I decided to use it to make the circuit as shown in the below circuit diagram.

    R1&R2=240Ohm &100 Ohm
    Those resistor where also salvaged from the ATX itself.
    So, I managed to get the inverter running but the issue is that the inverter runs only for a a few seconds since the neon bulb dims and fades out and I need to wait sometime before I can reconnect it. The transistors heat up and I doubt it is some kind of thermal shut in the transistor shutting it down. It does get pretty hot too if I try to run it long. What do I need to fix in this circuit?
    Thank you.
  2. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
    Fit heatsinks to the transistors?
  3. Rahulk70

    Thread Starter Member

    Dec 16, 2016
    The heat sink currently attached as shown in above pic was the one with those transistors itself in the ATX supply. I have another one but its quite large.Had used this one below previously for a mini peltier cooler. I'll try with this and see.
    IMG_20170214_132640.jpg IMG_20170214_132701.jpg