PROJECT to replace a vibrator in a ignition test instrument.

Thread Starter

debe

Joined Sep 21, 2010
1,389
Well 2 transistors in parallel didnt work too well @ 2A 7V. Just get too hot one 60degC & going mutch higher, the other one lagging by 10 deg C. Will just have to find better transistors i guess.DUAL Trans on heat sink.JPG
 

Alec_t

Joined Sep 17, 2013
14,264
Adding low value emitter resistors helps to balance the two transistors. Without those, one transistor will hog most of the current.
 

crutschow

Joined Mar 14, 2008
34,201
2 transistors in parallel didnt work too well @ 2A 7V. Just get too hot one 60degC
Why are you using an isolation pad under the transistors and what is it made of?
Did you use thermal grease to mount them?
Does the heatsink also get hot?
 

Thread Starter

debe

Joined Sep 21, 2010
1,389
The insulated pads are proper heat sink insulators & the heatsink gets almost as hot as the transistors. Have some MOSFETS coming & will try them next.
 

shortbus

Joined Sep 30, 2009
10,045
Gas stoves/cooktops emit a burst of igniting sparks when the knob is pressed. Available at appliance parts stores in many flavors. No vibrator, no circuitries, simple self contained and low cost.
What you show is just the part that sparks. If you look carefully they have a high voltage wire, like a spark plug wire but smaller in diameter connecting the sparker to a coil and circuit in the back of the stove. All of the burners and the oven use the same single coil and circuit to start the flames.
 

Thread Starter

debe

Joined Sep 21, 2010
1,389
Think i will go with MOSFET when they arrive, as another person on Smoke Stack forum is having beter success using a P chanel MOSFET.
 

Thread Starter

debe

Joined Sep 21, 2010
1,389
IRF9640 MOSFETs finaly arived & apear to do the job. Guted the old vibrator & using the shell as a heat sink & all the parts fit inside nicely. It doesnt get very hot at all 28deg C on 7V & 12V. Made the set up for simplicity & easy to construct.A1.jpgA2.JPGA3.JPGA4. NE555.JPGA5.  SMALL ENGINE COIL, on 7V.JPGA6.  CAR IGN COIL, on 12V.JPGA7.JPGA8.JPGA9.JPGA10.JPG
 
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