jgeidl

If it was a APC UPS you might drop them a note and ask them, they have been very helpful in the past in giving me information about transformers I have salvaged from their equipment. Jim

I am assuming that MCU programming isn't what you do everyday so I suggest you take a look at a Basic STAMP or a PICAXE chip. Through relatively minor programming you can accomplish what you are after. Jim

Try searching on cell phone remote control adn you will find all kinds of hits. Jim

I'm gonna ask everyone what may be a really dumb question; can I run this backwards. In other words, connect the 220VAC and expect to get regulated 12 VDC out the other side at fairly high amperage? Jim

Good for you! Looks nice and professional. Jim

Thanks Guys. I don't pretend to understand how you get from 19 VAC to 24VDC through rectification but will assume that to be true. Modifying the transformer is really not a practical possibility. These transformers are from UPSs so I am wondering how they do it; they provide the power to keep the internal battery charged. I may have to go to plan B...Oh, wait, I don't have a plan B. :-) How about a big honkin' Zener diode after the rectifiers and before the voltage regualtor? Jim

120VAC to 12VDC 25A power supply circuit needed

Try allied Electronics, www.alliedelec.com , they have about a million waterproof boxes in all kinds of sizes and shapes. Jim

Try Googling 7805 voltage regulator. This device with a few caps will control the output. There are about a million circuits out there using it as it is very common. Jim

The power supply will supply amerage up to it's rated amount automatically. Amerage output is determined by the "draw" of the components or circuits that are using the power supply. Jim

I'm sorry, I'm a dummy sometimes; I forgot to include the link. http://stores.ebay.com/PHAnderson-Electronics He also has a store outside of ebay, I think. Jim

Basil, You might want to take a look at the stuff this guy sells related to PICAXE. He has chips but, more importantly, he has prototyping boards that have a serial hookup and power supply on them so all you have to do is plug in the chip and program it. I have bought several things from him and he seems to be a good guy. Besides that, he is cheaper than the "official" US distributor for PICAXE. Jim

I fool around with BASIC Stamps too but discovered PICAXE chips the other day and think you might want to look at them for your application. They are SOOOOOooooo much cheaper and can be programmed using Basic. Jim

I think the next thing she ought to be buying is about 100 8 position SIP resistors! Jim

I have been following this thread to see the outcome. One thing, based on th elast drawing, that should be noted is that you are not working with 20 LED/resistor combinations in series, you are working with 20 LED/resistor combinations in parallel so you might want to rework the numbers a little. I am also really happy to see the transformer get into play. Runnig this circuit without a transformer is just asking for someone to get hurt real bad, as AG has pointed out earlier and repeatedly. As to cost, I can't help but wonder if a 12VDC wall-wort transformer and, maybe, a 7805 wouldn't be a quick, easy and cheaper solution to building the power supply cicuit. Even better would be 6VDC wall-wort. Just some thoughts... Jim

Plus, what is the current draw of the LED's you are using, there are a lot of different LED's out there. Jim

Take a look at the group linked below. You will have to join but it is free and they don't bury yoou in spam. http://tech.groups.yahoo.com/group/Homebrew_PCBs/ Jim

I'm not sure you will need any caps if you are using a battery for your supply. Perhaps others will have a comment on this. Jim

Try putting a diode across the MOSFET to direct the bounce when the motor direction (polarity) changes. Remember, the motor is just a big inductor and the change built up in it comes bouncing back when the current drops. Jim

Good for you. Do a Google search on LM317. This si a voltage regulator that is perfect for what you want to do. The datasheet has some good examples in it, as I recall. You will find a lot of hits for this part as it is fairly common. Jim

If you can tolerate a little more than 0V on the bottom end and a little less than 30V on the top end AND you don't have a burning dsire to build the whole thing yourself you might want to take a look at these power regulators on eBay: 250068727100 . I have used these several times and been very pleased with the results. Jim

You are going to need to put some parameters around this question. From what voltage to what voltage? AC or DC? How much amperage? Jim

Gayan, I can't help with your issue but would sure love to see a schematic when you are finished.

You will probably have more success searching on "DAB" in quotes. Jim

Ben, I gonna take a guess that what you are looking at is a diode and the "protection" you talk about is actually a heatsink which helps the part dissipate heat it builds up. As Ante suggested, upload a couple pictures and/or some of the numbers off the parts. Jim