Hi,
I'm a complete beginner to electronics, so please bear with me! I hope you can help with what I assume is quite a simple circuit
I'm trying to construct a variable output DC voltage regulator circuit. The input volage is 13.8v from a bench PSU (200W at 13.8v, so about 15A max).
I've used the tutorial on Afrotechmods' Youtue channel (here :
) as I found it very accessible. I prototyped then built the circuit using breadboard, then transferred to stripboard with no issues.
I used the exact components he uses (i.e. 0.1uf ceramic cap on the input and 1.0uf electrolytic cap on the output). I used a 510k resistor (http://www.maplin.co.uk/p/metal-film-06w-510k-ohm-resistor-m510k) for R1 and a 10k pot (http://www.maplin.co.uk/p/10kandohm...ure-fully-enclosed-preset-potentiometer-uh03d) for R2 so I could vary the output.
I tested, and as expected, with a 13.8v input, I could dial from about 7.6 to 10.9v approximately on the output, which was great.
However, the output current is extremely low. For the end project I need about 500mA, but I've been testing with devices that have much lower load than that, and it hasn't been able to even power these.
So, I put a Nichrome wire heater band for a telescope (that I know draws around 1.2A at 13.8v) on the output, and dialled the output all the way up to 10.9v, and the output current is only 0.1A when measured in-line with a multimeter. The regulator is getting hot, and there is SOME current on the output, so there is definitely something going on, but the heater band itself does't seem to even get warm.
I also tried linking up a child's toy (a small motorised car that takes 4x AA, so dialled the output back to 7.6v). The car makes the sounds it should, but these are extremely laboured as if there is virtually no power getting to it, and non of the LEDs etc light up. Again, I'm only seeing about 0.1A being drawn on the output, whereas Id expect to see much more.
I've checked and re-check the circuit, and it is correct as far as I can see. I have also changed the LM317T to make sure it wasn't that, but the results are the same.
I'm really confused!
Hope somebody can suggest something to my beginner's mind. I only have a multimeter to test with, so apologies for the lack of oscilloscope use for testing...
Thanks in advance!
I'm a complete beginner to electronics, so please bear with me! I hope you can help with what I assume is quite a simple circuit
I'm trying to construct a variable output DC voltage regulator circuit. The input volage is 13.8v from a bench PSU (200W at 13.8v, so about 15A max).
I've used the tutorial on Afrotechmods' Youtue channel (here :
I used the exact components he uses (i.e. 0.1uf ceramic cap on the input and 1.0uf electrolytic cap on the output). I used a 510k resistor (http://www.maplin.co.uk/p/metal-film-06w-510k-ohm-resistor-m510k) for R1 and a 10k pot (http://www.maplin.co.uk/p/10kandohm...ure-fully-enclosed-preset-potentiometer-uh03d) for R2 so I could vary the output.
I tested, and as expected, with a 13.8v input, I could dial from about 7.6 to 10.9v approximately on the output, which was great.
However, the output current is extremely low. For the end project I need about 500mA, but I've been testing with devices that have much lower load than that, and it hasn't been able to even power these.
So, I put a Nichrome wire heater band for a telescope (that I know draws around 1.2A at 13.8v) on the output, and dialled the output all the way up to 10.9v, and the output current is only 0.1A when measured in-line with a multimeter. The regulator is getting hot, and there is SOME current on the output, so there is definitely something going on, but the heater band itself does't seem to even get warm.
I also tried linking up a child's toy (a small motorised car that takes 4x AA, so dialled the output back to 7.6v). The car makes the sounds it should, but these are extremely laboured as if there is virtually no power getting to it, and non of the LEDs etc light up. Again, I'm only seeing about 0.1A being drawn on the output, whereas Id expect to see much more.
I've checked and re-check the circuit, and it is correct as far as I can see. I have also changed the LM317T to make sure it wasn't that, but the results are the same.
I'm really confused!
Hope somebody can suggest something to my beginner's mind. I only have a multimeter to test with, so apologies for the lack of oscilloscope use for testing...
Thanks in advance!
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