Hello, I installed that Chinese regulator and cannot get lower enough voltages. The seller don't understand because of the language barrier. It says in the add that it reaches -12 to -25 V, however I turned the trimpot and it doesn't get lower than -13.5V , I only want -12.5V max, my DC is -24V which I cannot lower.
First off, I hope you didn't pay $20 for a single regulator.... They're normally about $2.50....
Secondly, please be clear here, did you buy an LT337, or an LM7912? If its the 7912, as pinholer suggests, what do you measure, with no R1 or R2, and the regulator pin 1 tied directly to ground?
Secondly, please be clear here, did you buy an LT337, or an LM7912? If its the 7912, as pinholer suggests, what do you measure, with no R1 or R2, and the regulator pin 1 tied directly to ground?
The LM7912 is not intended as an adjustable regulator, but if its ground pin is grounded, the input is connected to -15 V or below, it should have no trouble delivering -12 V. So the circuit shown with the trimpot shorted and R1 plucked should work.
Tom
Tom
Tom, thanks, I should but it doesn't, it's a regulator with some pnp outputs, it has a trimpot, just out of range, it's a sochi tech lol
Did you connect and measure it with a minimum load of sorts?
As a master in chinglish (plus dealing with native speakers) I think some translations and meanings are not easy to understand. The regulator can be used for both LM337 and 79xx pinout (which are the same contrary to 78xx/LM317) and it is hinted to look carefully to the pinout. The LW79xx (its name!) has GND - Vin - Vout pinout and can be used in 79xx/LM337 situations but in LM337 situations R1 should be removed and a jumper for R2 should be installed. Apparently it has setting resistors onboard.
As a master in chinglish (plus dealing with native speakers) I think some translations and meanings are not easy to understand. The regulator can be used for both LM337 and 79xx pinout (which are the same contrary to 78xx/LM317) and it is hinted to look carefully to the pinout. The LW79xx (its name!) has GND - Vin - Vout pinout and can be used in 79xx/LM337 situations but in LM337 situations R1 should be removed and a jumper for R2 should be installed. Apparently it has setting resistors onboard.
Oh, so you're saying that the regulator is not an LM7912 but rather a $20 discrete implementation?
Have you tried setting it up as an LM7912 on a piece of prototype board or dead-bug style?
Tom
No... so it was a pitb to remove it, a newclassD -12V is on the way, but I still hope to make it work to replace the other dac regulator on the other reference dac.
I am sure there is one resistor that I could remove and switch and it would reach the target. pcm58 can go up to -13V, but -13.5 is too much, I don't even want to try.
I am sure there is one resistor that I could remove and switch and it would reach the target. pcm58 can go up to -13V, but -13.5 is too much, I don't even want to try.
Yep, I communicated back and forth with the seller hoping he has some clue how to fix the -25V version to cover -12V, all the way it is not going further than 13.5...
They are not there in true LM79xx situations 😉 and they are included on the new regulator PCB.
The clou is that the module has a confusing name. In the left picture a LM337 situation with setting resistors is pictured. At the right the “79XX” called module (yes its typenumber/name is 79XX) is used instead of the previous LM337. Then R1 must be removed and R2 replaced for a jumper. So in fact the module called “79XX” is then wired like a true LM79xx…..with LM337 or better performance (no guarantees).
In case of replacing a true LM79xx the module called “79XX” can just be soldered in. Of course someone that can apply logic would first connect it outside the device and set it to the right voltage as output voltage should not be a question mark.
It is more an IQ test/jigsaw puzzle than a regulator the way it has been advertised, called and pictured in a schematic 😀 High risk of damaging stuff when soldering in randomly.
The clou is that the module has a confusing name. In the left picture a LM337 situation with setting resistors is pictured. At the right the “79XX” called module (yes its typenumber/name is 79XX) is used instead of the previous LM337. Then R1 must be removed and R2 replaced for a jumper. So in fact the module called “79XX” is then wired like a true LM79xx…..with LM337 or better performance (no guarantees).
In case of replacing a true LM79xx the module called “79XX” can just be soldered in. Of course someone that can apply logic would first connect it outside the device and set it to the right voltage as output voltage should not be a question mark.
It is more an IQ test/jigsaw puzzle than a regulator the way it has been advertised, called and pictured in a schematic 😀 High risk of damaging stuff when soldering in randomly.
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Told you I can deal with both chinglish and native English speakers and cross translate that to a few other languages. If you survive that language wise then you can communicate in Africa too. Languages are simply magical when you get a grasp of a few but the surprise is that lines are only rarely 100% straight. The colossal misunderstandings while everyone thought to have a mutual agreement are the very best 🙂
Just suppose they had called it "Sochi Tech Minus" everywhere then less people would misunderstand.
With regards to the insufficient output range that will likely be a 1 resistor affair. Try/experiment off board with a test PSU that has a current limiter.
Just suppose they had called it "Sochi Tech Minus" everywhere then less people would misunderstand.
With regards to the insufficient output range that will likely be a 1 resistor affair. Try/experiment off board with a test PSU that has a current limiter.
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