Hello,
I have made a few of these kitchen timers…no issues at all and very impressed with them…
However, I recently thought to swap out the LEDs for particular timepoints…such as the ten-minute one, for a different colour to make it a little easier to see these more crucial time points (for me) from a distance…no worries you would think, but after playing around a bit, things got a bit messy and then suddenly the entire timer died and refused to be resuscitated…
I thought perhaps I’d shorted out something and also noticed that the IC was really hot…I ordered two more kits, and went really slowly…each LED was working fine, but when coming to the 10-minute one, which I changed to green instead of red, it suddenly died again…I thought perhaps this problem may be something to do with the colour change (unlikely I know) because there was no issue at all with the previous colours (minutes 1–9), so went slowly for a repeat go with a new kit and using only the original red colours…again a problem with the led 10! And as for all previous problem attempts, the IC was REALLY hot (yet under a deep microscopic analysis, I could not see any shorts etc…all LEDs were correctly orientated etc.)…
So, I had to think what I was doing differently, and my supposition was that it might be related to the fact that because I wanted to solder each LED and then see it function, I had it powered up to a 4.5 volt connection (I do this rather than use batteries so that I never have to change batteries—an approach that had worked well for previous kitchen timer kits) as I was doing the soldering. That didn’t seem to be an issue as I was soldering, and then checking, the first 9 LEDS…but some issue was leading to the IC being fried around that LED 10.
So, I guess the thing to do is just to buy another kit and then do all the soldering of all the LEDS and only then power it up and check that all is working. And I suppose that in some way, this might be good news (!) because my issues appear to be due to having it powered on while soldering, and that I can in fact make these LED colour changes where I want, as long as I don’t apply power before completing all LEDs. Would you kindly fellow electronics aficionados agree with that assumption before I splash out on another kit?!