Hello all. New here, so please be gentle...
Just wanted to poll opinion on a very simple little LED/2N2222A transistor as switch design I've come up with (see attachment).
The output of a low frequency relaxation oscillator (implemented with a 2n2646 unijunction) is fed in via the 300K resistor to switch the transistor on and off and flash the LED. It is part of an audio circuit and I've found it necessary to add a 4u7 at the base of the transistor to filter the hard edge off the oscillator and stop it from feeding through to the audio (without it you can hear the oscillator ticking away).
I've breadboarded it and it works nicely, but am thinking - do I need some current limiting (like a small resistor from emitter to ground) to protect the transistor from discharge through the base-emitter from the 4u7 cap? Or maybe there's a slightly better way ...
Just wanted to poll opinion on a very simple little LED/2N2222A transistor as switch design I've come up with (see attachment).
The output of a low frequency relaxation oscillator (implemented with a 2n2646 unijunction) is fed in via the 300K resistor to switch the transistor on and off and flash the LED. It is part of an audio circuit and I've found it necessary to add a 4u7 at the base of the transistor to filter the hard edge off the oscillator and stop it from feeding through to the audio (without it you can hear the oscillator ticking away).
I've breadboarded it and it works nicely, but am thinking - do I need some current limiting (like a small resistor from emitter to ground) to protect the transistor from discharge through the base-emitter from the 4u7 cap? Or maybe there's a slightly better way ...