The *root* cause is plainly the set of fluorescent lights in the garage being switched on or off (or both) via a simple relay controlled circuit of mine . But what I'm really seeking advice about is how to establish why that has suddenly started causing malfunction in *another* circuit.
In my lounge I have an infra-red remote control unit I made about 25 years ago. Push buttons in the battery powered remote toggle various lamps, TV, hi-fi, etc via relays. (Not the garage lamps, which use an independent circuit.) It has its own DC power supply derived from the mains. Very reliable previously. But now, every time I return from the garage after using the light circuit, chaos reigns. Various units are switched on and don't respond to the remote. Removing mains power from the master unit for a few seconds restores normality (sometimes after two attempts).
The garage unit, powered from the mains, switches 4 parallel wired fluorescent tubes of various types if any of several buttons are tapped.
Access to the lounge unit is difficult and so before doing that and opening up the master unit and trying to understand my 25 year old circuit notes I'm seeking practical tips on how I can optimise the forensic work please.
For example, which of these is more likely?
- The source noise from the garage lamps has suddenly increased
- The DC supply to the remote control receiver and relay circuitry has suddenly become noisy.
What simple tests can I make to help me isolate the cause please? My 'scope (barely portable) is in my now rarely used shed/workshop, so I'd prefer not to be dependent on that in this context.