Lessons learned the hard way

[wwdotme]

Ok is thier any other way to protect the transistor besides
a neon light?
My small neon does not safe guard my transistor is the lesson learned to night after 3 transistors being burnt out. I hooked up a charge battery on my last transistor to make sure the charge had a place to go and every thing was great...
The light still lights up if you plug it in to the wall socket for ac. But never does light up on my larger fan motor.

ww

[sucahyo]

Have you run it without load? How many amp that goes to the transistor? I usually calculate it with:
Transistor amp = input voltage / Coil resistance

Running radiant oscillator with low coil resistance without recovery part can toast transistor immediately, especially at high transistor gain. Maybe you need higher resistance for base to limit current.

Make sure the voltage between base to emittor or collector never exceed 7V, limit it with resistor. Also make sure the current never exceed 10 Amp for most switching transistor.

[tai61]

wwdotme

Ok is thier any other way to protect the transistor besides
a neon light?
My small neon does not safe guard my transistor is the lesson learned to night after 3 transistors being burnt out. I hooked up a charge battery on my last transistor to make sure the charge had a place to go and every thing was great...
The light still lights up if you plug it in to the wall socket for ac. But never does light up on my larger fan motor.

ww

try 2 neons in series ,works a treat,your meter will show small volts thru the base but the neons need 90v to glow,go figure, cheers bill

[wwdotme]

well I need to get this one up so I can get some actual readings.
The last transistor was my fault clutttered work area accidently unhooked the charge batter and poof.
2 neons will have to try that..
add more resistance? not really sure where so will get it up and get some readings.
was charging my drill battery pretty good I thought .o1 volt every 20-30 seconds.
thanks guys your a great help!

[Sephiroth]

try 2 neons in series ,works a treat,your meter will show small volts thru the base but the neons need 90v to glow,go figure, cheers bill

But if you put the neons in series then it will need 180v to conduct... that means 180v spikes hitting the transistor instead of 90v

ww - you could try a zener diode... perhaps around 30-40v? But I don't know how long a zener can survive the spikes either...

[wwdotme]

Up and running again!!

couple readings after running for half hour

2-13-09
input 10.73 steady
output c to e 9.61 steady
output c to b 10.52 steady
input .9 amps
charge to drill battery pack 9.37 climbing slowly
.35 amps output
counterclock wise rotation

rotating clock wise pulls .8 amps
seems to charge a little bit slower.
9.56 on c to e
10.44 on c to b
.3 amps output into to battery