LCR Cal Test PCB

[KungFuJosh]

My old version (I think V1) of the Cal Test PCB went up to 1GΩ so I was able to test 100MΩ on there. It shows about ~80MΩ, so 20% less than the nominal value. Whether it's actually off or not, I don't know, but it does tell us that only the 1M and 10M ranges are goofy.

[KungFuJosh]

Looks like the 100M range is probably ok on the 3532-50. At 1kHz, the IM3570 is reasonably close.

At 5Hz the IM3570 reads it verry niiiice.

[KungFuJosh]

Here's the Gerbers and BOM for the LCR Cal Test V5 PCB.

BOM updated again. Mouser incorrectly had 100nH listed on what was actually a 100µH inductor. This is why I always test all parts, no matter where they come from.

[Kean]

BOM updated again. Mouser incorrectly had 100nH listed on what was actually a 100µH inductor. This is why I always test all parts, no matter where they come from.

For those playing along...
The wrong part is Murata LQM21DN101M70L - listed as 100 nH, but actually 100 uH (I've reported the error on website)
The replacement is TDK TMS201610ALM-R10MTAA - confirmed as 100nH on datasheet. It is 2016 metric so 0806 rather than 0805 - close enough.

I haven't ordered the parts or PCBs yet, but probably will next week.
If anyone else in Australia wants one, I may have some PCBs and parts available.  I probably won't buy multiples of all parts, as it works out about AUD $50 per set.

[KungFuJosh]

I probably won't buy multiples of all parts, as it works out about AUD $50 per set.

For the cheap stuff, get multiples, especially the 0805 stuff. I find at least 1 or 2 0805 goes flying across the room per project. 🤣

[KungFuJosh]

I got the replacement 100nH in today, and it looks good.

[watchmaker]

Thanks for the board Josh.  Just ordered the parts; both Mouser and Digikey are backordered on the 10v  1000uF Tant.

[KungFuJosh]

Thanks for the board Josh.  Just ordered the parts; both Mouser and Digikey are backordered on the 10v  1000uF Tant.

You're welcome!

I added an alternate 1000uF cap to the BOM, see if you can get them to add it to your order, or swap them out.

[KungFuJosh]

For anybody curious about the Step D Factor test results, here's what to expect with the Panasonic resistors in the BOM:

Measured cap + standard values:
29Ω = 0.00018 (cap only YMMV - test your cap and adjust the rest)
79Ω = 0.00049 (29Ω + 50Ω)
162Ω = 0.00101 (29Ω + 133Ω)
797Ω = 0.00506 (29Ω + 768Ω)
1609Ω = 0.01010 (29Ω + 1.58k)
16029Ω = 0.10071 (29Ω + 16k)
160029Ω = 1.00530 (29Ω + 160k)

[KungFuJosh]

For anybody else wondering:

Wah inductors are for Wah Wah guitar pedals. Typically 500mH to 700mH. You can google "Wah Inductor," or look for "Red Fasel inductor" if you want to populate that.

Thanks,
Josh

[watchmaker]

OK Josh, I am ready to populate your board.

My first attempt at SMDs.  Thankfully I am used to screws smaller than 402.  All the ckt does is running lites, but it gave me confidence.  The trace from pin 7 of the 555 to the caps was bad; that took more time than soldering.

I even replaced the 555 before finding the issue.  Now I know I can desolder as well.

You certainly need tweezers for measuring SMD caps.

Was trying to figure out what EEE stood for until I realized it 333!  Lot to learn.

[KungFuJosh]

My first attempt at SMDs. 

I've done a few of those test/learning boards before I got into SMT. It really is helpful.

The good news is that my LCR boards are generally hand-solder pads, so you have extra room to solder if you don't have hot air.

Thanks,
Josh

[Martin72]

I've done a few of those test/learning boards before I got into SMT. It really is helpful.

I still remember my first attempt over 10 years ago....
Test board, SMD solder paste applied, then various 1206 capacitors placed on the corresponding pads.
And then I switched on the “SMD hot air tool” from the lab, held it on - and all the capacitors blew away with it....

[KungFuJosh]

I still remember my first attempt over 10 years ago....
Test board, SMD solder paste applied, then various 1206 capacitors placed on the corresponding pads.
And then I switched on the “SMD hot air tool” from the lab, held it on - and all the capacitors blew away with it....

  Classic!

The boards I used went down to 0402 and 0603. I watched a youtube video before attempting, and it said to be careful of the hot air pressure. 😉

[watchmaker]

Interesting.  I do have a got air gun but I just used my Ersa Pico.  I put some solder on one pad, pinned one end or one leg and did the other(s) and went back.

Also used flux paste applied with toothpick at times.

What are the ways this task is done?  Given the cost differential, I can see the advantages of SMDs.  OTOH, not sure I want to go down the rabbit hole of PCB design.  I wonder if I could do something using protoboard?

[KungFuJosh]

That's a good start. There are other videos, but in general, Pace has awesome stuff.

Martin should pay attention to this one too. 😉😉