I have a single transistor relay amplifier driven by GPIO output of Raspberry PI. The amplifier works reliably and is not causing any immediate problems. Still, if I leave the relay flipping on/off every second, the computer board somehow gets reset after an hour or about. I suspect that my relay still generates too much noise and I need to take more measures then just a flyback diode which I already include.
Would adding a capacitor between base and emitter of the transistor help? By idea, when GPIO level changes, this capacitor should cause gradual closing/opening of the transistor rather than abrupt. This would give much more time for the flyback diode to engage. I understand this would slow down the switching, but 200 ms or about delay is acceptable for this relay.
If you think this would work, that would be a recommended capacity of this capacitor?
Please also tell if could do something else can be done to make this amplifier really quiet. I cannot easily get rid of the relay because the circuit it controls is totally undocumented (no clue about the voltage, current, polarity, requirements, just that < 12 V and this is a signal circuit so unlikely a lot of current). I only have a single power source to power up both computer and amplifier.
I currently have no oscilloscope in my disposition so my possibilities to investigate the noise spikes are limited.