I'm not sure if I understand you correctly. But with a 15W 0.47 ohm resistor I could theoretically use 5.64A

15W resistors cost more than 2W or 5W resistors. The supply was designed for up to 3A, so you can't expect to operate at 5A without experiencing issues.

You could install a 50W resistor and not make a difference in performance.

 

That's right. I've read some blogs and posts about how to improve this kit, one of the things they mentioned was increasing this resistor. I understand it more as a safety buffer, e.g. in terms of temperature, not for use more power. As far as I understand, some components are at their limit at the specified 30v and 3A. As well as the TL081 which I had already changed.

I won't use it at its maximum specs. Maximum 20V and 2A I think.

 

That's right. I've read some blogs and posts about how to improve this kit, one of the things they mentioned was increasing this resistor.

You can't believe everything you read on the internet. A 5W resistor for current sensing was operating well within its ratings. The 5W rating is only applicable for operating at room temperature. It needs to be derated when operating at higher temperatures and its power rating will drop to 0W at some high temperature.

This is for Yaego cement resistors:


At 70C, you need to derate by almost 20%. That's how I arrived at the derate factor mentioned above.

Using a higher wattage resistor would just make you look silly.

I won't use it at its maximum specs. Maximum 20V and 2A I think.

That's probably a good idea. Looking at that circuit with a 24VAC input kept making me cringe. The absolute maximum supply voltage for TL071 is +/-18V (36V differential). With a loaded 24VAC transformer, the supply differential would be larger than that. It's worse for a lightly loaded transformer because the secondary voltage would be higher than nominal.

We don't normally operate any device at its absolute maximum ratings because they're not guaranteed to survive them.

 

Using a higher wattage resistor would just make you look silly.

Ok i understand, I leave the resistor as it is now.

We don't normally operate any device at its absolute maximum ratings because they're not guaranteed to survive them.

I have another AC power supply for the board here 18V 1A. I will use that too.

 

I have another AC power supply for the board here 18V 1A. I will use that too.

Do you mean 18VAC? That power supply won't work with a DC input.

 

Yes 18VAC 1A, i would use it for small Projects with low need of current, instead the 24VAC 3A.

This Power Supply Kit needs AC as Input !

 

18VAC 1A

Another thing to consider is that you won't get the rated current from the transformer. With a bridge rectifier, you won't get 100% of the rated current.

This is from Hammond:

 

Ok good to know. But for little ESP8266/32 projects it is enough. If i need more, than i can use the bigger one with 3A.

 

Hello,

I'm a Newbie to electrical engineering and I bought 2 DIY kits. One on Aliexpress which works without any problems and one from Ebay where I only get 33 mA current from the power supply. I can only drive a small LED with it, if I connect a small DC motor it immediately goes into the limit and the red LED lights up. With the other Board, the DC motor runs without problems and everything can be adjusted as desired.

I have already read a lot here and found the PDF file operation-and-maintenance.pdf with various measuring points. I have measured all the points given there and all values are correct. I have already exchanged the 3 OP Amps TL081 with MC34071 but the problem remains.

I use an external power supply AC 24V 3A for the input of the boards.

If I don't connect anything to the output, I can regulate the voltage quite normally, it also works with the connected LED and 2 connected resistors, I can regulate voltage and current, but current no more than 33 mA. The 33 mA i measured with my multimeter, which I connected to the output alone. I have checked various components, everything is soldered correctly as on the working board. I can't find anything wrong and I don't know where to look.

I still don't understand the circuit diagrams that I found on the net and here, so I have problems finding out the cause.

Do you have an idea which components I could check to solve the problem and make it work like the other one ?


Best Regards

Stefan

Send it back and hold ur money for the real one

 

Send it back and hold ur money for the real one

He replaced a wrong resistor value and it's fixed.