EP 117 - SINAD meter - Build and test - Part1. 

Thanks

Thanks , i cant see your other comment you made , did you delete it ?

Hi , yes a 50ua meter will be fine, thats what i used.

I might offer a board and component kit for the spare boards i have , meter and box etc would have to be obtained

I'll sell you a meter

I would be interested in a kit at a sensible price

Im not going to compete with you and your meters, you have made a decent product there and im not going to go into competition with you .

It’s on part 2

@@MicroChipz Thank You

There’s going to be a few more videos on this . It’s not working right somethjng strange going on. The rubbish schematic didn’t help either .

@@MicroChipz I may have found a better schematic, if you do a search for SINADDER schematic / service manual this is a unit that was in production based on the Motorola design. It uses J113 FETs which are still available by ON semi. The circuit is also based around the LM348 quad op amp. Also if was me I would dump the zener and fit a modern low drop out 9v reg. I think it would be easy enough to build a nice digital bar graph display rather than a meter. Just an idea. Looks like a great little project.

@@M0XFXUK yes I have the Motorola schematic and I might have a pcb on the way , and for the display yes I was thinking of a led bar graph , just need to get it working .

@@MicroChipz Hi this project really hooked me, I think it's a great project. I have taken a look of what I can see of your schematic. I think your problem is in the later stage of the AGC, I am trying to figure out why diode and biasing arrangement is like it is because it doesn't look right to me. I think this is causing the waveform clipping. Look at the Sinadder circuit they have done away with the potential divider circuit. I think the Sinadder is a more modern design of the old Motorola R-1013A, I am going to have a crack at building it. What PCB design software do you use as I use Eagle. I can send over the board and schematic files if they are of any help to you. Also I would be interested in looking at the schematic you are using as I can only see bits of it from the video. Best Regards John

Il send a link later

Thank you . sub returned :)

I think the Motorola one uses 10v and knoxiemans used a different one , the circuits are basically the same . A zener is more than enough to regulate . The whole circuit draws very little current .

@@MicroChipz Yes the one I have a circuit for the Sinadder 3 uses a low power 78L08 100 mA regulator, they all seem the same circuit really. Not too sure about the missing capacitor on the voltage divisor for the +/- 6 volt, think something else must be going on, as it has a capacitor across the two resistors. Ken

Yeh I’m not sure why mine require the cap, I did make a moto board . Removing the same cap caused a little disruption , not as much as the other board .