Curiosity teardown: landscape lighting power supply

[@retireeelectronics2649]

Nice find and salvage. Totally agree on the switching power supplies, so much noise. A long time ago all you had to worry about was 60Hz sneaking in.

[@ohmbug10]

Nice find. You could parallel the primaries and series the secondaries to get 24V Center Tapped.

[@TheUnofficialMaker]

great find

[@richardturton6900]

Unknown chip could be a microcontroller, maybe a 8 bit PIC16 or a clone?

[@DustinWatts]

I would also keep the rotary switch the good ones are not cheap! :D Ow and two transformers give you a centre tap.

[@garymucher4082]

You sound like me. I scrap everything. I really like microwave transformers since you can rewind them into basically any output you want. And that is why I have so many transformers laying around. Linear power supplies are heavy, but can give you very clean outputs with proper circuitry. And who doesn't have some project to build...one day?

[@darrenchapman7203]

Love a free transformer. That chip gives me Pic16f84 vibes.

[@albanana683]

I do love an old skool linear power supply. A good source can be had from just replacing your step down transformers in 12V halogen lamps with switched mode equivalents, bonus points if you can also change the halogens for LED. I scavenged a very meaty 250VA toroidal transformer from a set of 12 x 20W halogen lights, that got replaced with a matchbox sized PSU and 12 x 3W LEDs for about 1/10th the price. No brainer, as long as you don't need dimming.

[@brianmarshall948]

Mystery chip is likely a 556, dual 555. One section would be the timer, and the comparator in the other, used for the light sensing circuit.

[@mavis34]

At a last resort, I usually use google lens on stuff I cant find the normal way. Sometimes it works....

[@registromalplena2514]

I can't remember the number now, but there was a 555 timer that had a built-in register that could be used as a divider so you could have accurate but very long timings. Or if you increase the frequency of the 555 very accurate shorter timings. Thought the chip started with XC or XR something?

[@registromalplena2514]

XR 2240

[@acehart2]

Very useful to by new costs so much

[@frankowalker4662]

I'd have done the same, just turn them into 12VAC transformers in a nice case. (And add an on/off switch and power light)

[@309electronics5]

That chips is probably some microcontroller or Asic or in less common cases a Logic ic but google lens and google goes dry so i cant find anything about it. Maybe usefull to take a few hundred looks at the pcb and pinout and seeing if you can trace the chip, although that aint worth the time

[@frenchcreekvalley]

What about rewinding microwave oven transformers for beefy linear power supplies?

[@pileofstuff]

That's a possibility. The microwaves I've taken apart so far all had a switching power supply, so no beefy transformer on those.

[@frenchcreekvalley]

@@pileofstuff I was going to mention that you need to find the older junkers. i have been pretty lucky so far. All you have to do is to lift the thing to tell whether it's old enough.

[@tenminutetokyo2643]

Wait Chong caps. They’re known to explode.

[@pileofstuff]

These must have ben a good batch - they lasted for a few decades so far.