amanitavirosalt - 2-12-2025 at 14:03
I'm trying to set up a basic slayer exciter circuit, but it's not oscillating from what I can tell. Using a basic 2n2222 transistor, 47k resistor, and
a white LED as the diode, but the LED won't turn on, telling me the circuit is not oscillating like it's supposed to. Can anyone help with this?
Sir_Gawain - 2-12-2025 at 14:08
Check your secondary feedback connection
[Edited on 12-2-2025 by Sir_Gawain]
in order of likelyhood :
Sulaiman - 2-12-2025 at 15:42
blown transistor
reverse phase primary
wiring error
bnull - 5-12-2025 at 04:25
It is hard to know just by looking at that picture. Could you please make a diagram of your wiring?
In any case, you can (1) reverse the LED connections because you may have put it backwards (I do that all the time), (2) use a different LED (red, for
example) or (3) a diode proper. If it still doesn't work with that old fart 1N4001, then the problem is elsewhere in the circuit.
[Edited on 5-12-2025 by bnull]
semiconductive - 7-12-2025 at 14:17
1) you need positive feedback.
The flat side of the transistor is not visible in the picture, but it needs to be aimed to the RIGHT side of the board. This means the EMITTER in
near the bottom of the board. Row 29=Emitter, Row 27=base, Row 25=emitter.
If you've hooked up the transistor backward, and you have more than a 5 volts for a power supply; the transistor you have will likely be damaged and
you'll likely need to replace it.
2) The low winds coil's orientation to the high winds coil matters. I think your excitation coil has yellow and white soldered leads plugged into
the board. Swapping the yellow and white leads will reverse the polarity of the coil and might cause oscillation ( if you have it backward. )
3) The 47K ohm resistor is so large you may not be able to see the LED light up. Assuming 9V power supply, 9V/47K = 190 [ uA ]. Red LED's take
about 1 [mA] to dimly glow and barely be seen in a well lit room. You're possibly 10 times smaller than that and in a well lit room. I wouldn't
expect you to be able to see a white high power LED.
You can test the LED:
If you remove the transistor and reverse the LED, I would expect you to see an extremely dim glow with the lights dimmed/or out in the room. If you
don't then the LED you've chosen is too high powered for that circuit. A red LED or gallium aluminum arsenide LED is a better choice than a generic
white LED.
Which ever way the LED glows when hooked to the resistor, alone, (no transistor in circuit) the correct LED orientation for oscillation is opposite of
what makes it glow with no transistor in the circuit.
Also: A tiny signal rectifier numbered 1N4148 or 1N4448 in a glass package is an even better choice for easier oscillation starting than a small RED
led.
190 [ uA ] x beta of 100 = 19 [mA] going to the coil.
The total operating current is small enough that you can put your white LED's anode from the +power supply to say row 20 of your prototype board; the
'arrow' of the diode points away from the +power supply and into row 20. Then you can move the yellow lead over to the LED to row 20. This should
cause the LED to glow brightly but shouldn't damage it.
If it does glow brightly, then I'd get a regular 1N4148 or 1N4448 small signal diode and wire that from the emitter of the transistor to it's base.
From row 27 to row 25, with black band of diode aimed to row 25. This should cause the LED brightness to DIM when oscillation starts.
[Edited on 7-12-2025 by semiconductive]