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will try a LM338K...5A with 7A peak...should be plenty...thanks MrAl!!!

cp out

Thank you guys, your right. I am going to build something with a LM330 power transitor.

Thanks again.

Hello Mr. Al!!! I am trying to decrease the output of a 120V AC/DC 3-12V variable output, 4A switching power supply down to around a 1 V-8V range. :grin: I tried attaching a 10 Ohm, 10W ceramic block resistor but this did not drop the voltage at all when measured by an Ohm Meter. Could my resistor b...

Kind Sirs:

I would like to drop 3.3V, 3As down to 1V, 3A with a ceramic resistor if possible. Could someone show me the correct way to figure out the proper value of the resistor and its watts?

Thank you.

Could anyone suggest a very nice TO-3 heatsink that they approve of?

Yeah Chris talking op temps of 95F to 140F. (Nice pooch.) Man I hope Mr. Al doesn't kill me. I have been assuming you guys have been talking F instead of C the whole time. Looking at Mr. Al's theoretical calculations now everything is actually running cooler than expected!!!! (emoticon for extreme e...

Wow what a great community there is on this board-everyone truly is interested in a lowly beginner and so helpful. This is a little embarrassing but I noted that with a moderate airflow over the heatsinks they now stay below 95 degree F on the voltage controlled voltage amplifier (12V, -12V supply, ...

I actually built one protoboard with a breadboard and then a second hardwired board. Tested both under actual conditions but unfortunately not long enough! Anyhow did the heat test tonight. Added a 3 inch heatsink, the largest I could find, attached it to the LM338 with heatsink compound and solid b...

thanks Philba and Robert...will pickup a larger heat sink today and then take some readings- very informative. I am committed to this approch now but I know PWM is used freqently too.

Dear Mr. Al I am using a smaller heat sink for the 338K TO-3 that is diamond shape with slotted vertical fins and about 2in long 1in wide and 2 in high so it would not take too much space on the board and it was the most common one I found. I will pick up a digital thermometer tonight but I know it ...

A little note is if I change the circuit input voltage from 12V to 9V, the 338 doesn't even get warm...Probably takes most of the work away from the 338(?)

Hi Chris- nice big one, this one really does boil...it is so far below it's rated cap (-3X) I can't believe it should get that hot, I haven't be daring enough to see if it hits thermal shutdown but I believe it would.

Mr. Al you recently spent an tremendous effort helping me get this circuit working exceptionally. I have a problem now in actual usage which maybe you could offer a few suggestions. The circuit powers a 12V, 30W, max 3A hydraulic solenoid. The 338K and large heatsink gets very "hot" (too h...

Has anyone ever played with the idea of DIY touch screen circuits.? Possibly infrared LED? I have 5, 17" monitors I would like to do so to without spending a lot of $$$ on.

Thanks you!

Perfect Thank you so much Al. Really sweet. The R3 gets a little warm, would it be as easy as just going to a 1.0 or 2.0 watt?? In case I want change the max output from 0-8V to 0-6V which resistor(s) would that be? You have a friend for life in Orange County Ca. / flightlinemail@cox.net Free Root C...