[keanecn]

As the MAX9926 chip is too expensive and SMD is not convenient for handmade, I am looking for an alternative VR COND. I saw a post on the forum viewtopic.php?t=3841&hilit=358 , so I drew a circuit board based on the schematic diagram provided by Sepehr20mg10 and made a finished product, but it doesn't work. I tried to read the signal with an oscilloscope, but there was no signal output. Could you please help me check if my copied schematic diagram is correct and if the components are soldered correctly? I am a beginner and this is my first attempt to draw a schematic diagram and make a circuit board, so I don't know much about it.

[keanecn]

The picture above is the schematic diagram I copied and the circuit board I made, as well as the finished product. The pins are defined according to the pinout of the 9926 small board. However, it doesn't work when I plug it into the Speeduino. Could you please help me identify the specific issues?

[digmorepaka]

The picture above is the schematic diagram I copied and the circuit board I made, as well as the finished product. The pins are defined according to the pinout of the 9926 small board. However, it doesn't work when I plug it into the Speeduino. Could you please help me identify the specific issues?

As always, work systematically.

Step 1. Visual inspection, did you solder everything properly? are any pins bridged? I'd double make sure that the pins on the fet aren't bridged, narrow TO92 pattern sucks for hand soldering, for future designs use the wide one whenever possible.

Step 2. Now that you know that there isn't anything exploded or not soldered, or the wrong way around, check if you are receiving power and ground where you expect it.

Step 3. Analog, Go step by step in the circuit, Do you see what you expect behind the input resistors? Is there what you expect on the input of the op amp? does the op amp output make sense compared to it's input? Is the output fet switching when it should?

On analog circuits like this it also helps drawing it in a circuit simulator like falstad and cross comparing when you aren't sure.

[keanecn]

The picture above is the schematic diagram I copied and the circuit board I made, as well as the finished product. The pins are defined according to the pinout of the 9926 small board. However, it doesn't work when I plug it into the Speeduino. Could you please help me identify the specific issues?

As always, work systematically.

Step 1. Visual inspection, did you solder everything properly? are any pins bridged? I'd double make sure that the pins on the fet aren't bridged, narrow TO92 pattern sucks for hand soldering, for future designs use the wide one whenever possible.

Step 2. Now that you know that there isn't anything exploded or not soldered, or the wrong way around, check if you are receiving power and ground where you expect it.

Step 3. Analog, Go step by step in the circuit, Do you see what you expect behind the input resistors? Is there what you expect on the input of the op amp? does the op amp output make sense compared to it's input? Is the output fet switching when it should?

On analog circuits like this it also helps drawing it in a circuit simulator like falstad and cross comparing when you aren't sure.

I'm not very skilled and I think the soldering and wiring are correct. But there might be mistakes in the schematic diagram from the beginning. I need someone knowledgeable to help me check the schematic diagram, PCB, and components for any errors. I'm just getting started with this and I don't understand it very well.

[digmorepaka]

I'm not very skilled and I think the soldering and wiring are correct. But there might be mistakes in the schematic diagram from the beginning. I need someone knowledgeable to help me check the schematic diagram, PCB, and components for any errors. I'm just getting started with this and I don't understand it very well.

Schematic looks fine. Follow the steps I outlined, you may discover that it's something dumb. Also sanity check, is your jumper configuration correct?

[keanecn]

I'm not very skilled and I think the soldering and wiring are correct. But there might be mistakes in the schematic diagram from the beginning. I need someone knowledgeable to help me check the schematic diagram, PCB, and components for any errors. I'm just getting started with this and I don't understand it very well.

Schematic looks fine. Follow the steps I outlined, you may discover that it's something dumb. Also sanity check, is your jumper configuration correct?

However, he just won't work. There's no waveform output at all. I can't figure out why.