I’m trying to build a esp8266 weather station and got some MCP1700-3302E to power the esp8266 from a lipo. But when I connect the lipo to the MCP1700 (looking at it flat spot at the front, ground left, Vin in the middle and Vout on the right) I get no output at Vout. I googled and could not find anything. I tested 5 different...
I’m not saying that your LDOs are fried. What I am saying is that some LDOs don’t take too kindly on not having the company of some nice caps.
What just caught my eye is that the datasheet specifies ceramic non-polar caps. That seems a bit weird. Just drawing a non-polar would have made sense, but specifying that it is a ceramic is strange. Using a ceramic makes sense, I mean there are 5 times the ceramic 1uF caps on digikey than there are electrolytics, but it should be technologically agnostic… I’d probably try to get some 1uF ceramics for testing.
The “typical application circuits” on page 2 in the datasheet ww1.microchip.com/…/MCP1700-Data-Sheet-20001826F.… shows both input and output being decoupled with a 1µF cap, have you tried that? I haven’t worked with the MCP1700, but I have had other LDOs fry themselves because the decoupling malfunctioned.
I’ve recently acquired an uncalibrated Philips PM2534 (edit: the battery-backed factory calibration data was lost due to the battery running out). I’m looking into somehow getting it calibrated. However, the calibration procedure is rather involved, and requires such things as an exact 300V DC (the service manual recommends...
400? I guess that’s in the ballpark I expected it to be.
I haven’t studied the BOM for the DIY solution, but something tells me that you’ll only be able to keep the cost lower than 400, if you value your time at close to zero.
With all that negativity out of the way, I’d definitely want to build it myself too. Although my anxiety level is exponentially correlated to the working DC voltage and at 300VDC I’m definitely well in the thick rubbergloves territory. Be careful with the build!
Easy, you import this puppy www.ebay.com/itm/305042665748 and set up your own business offering calibration services to recoup the cost. Then you can apply for the calibration engineer position at Minerva.
Jokes aside, have you contacted a calibration lab? I don’t know what it’s going to cost, but I can’t think of another way, if you’re not going to built the sources yourself. There’s one in the Netherlands www.minerva-calibration.com/calibration-service/
It would seem from a quick google that I’m not alone in my conclusion. But at least I have found an article explaining the build of the sources you need wolfalex.bplaced.net/…/calibrator.htm
Solution: @DJPhil has made some really insightful comments below, which are really useful. If you just want the cap you can set the parametric searches for 660uF, or in September 2023 I’ve found that digikey stock(s/ed) chemi-con EKHJ451VSN661MA59M....
I concur on the retrofit. It’s a two layer board, and the negative and positive rails are on opposite sides. I should be able to reuse the slot for the negative rail and make a slot for the positive (bottom side) rail. That way I can still get snapin terminals, as I’m concerned about the cross section of terminals if I had to resort to some round ø1.0mm pins.
I considered the approach you suggest with turning the terminals on the rivet, but all the riveted terminals I’ve seen have been potted partly, so I’d be concerned that turning them would put stress on the rivet and internal connection. That hasn’t been an issue for you? Anyway the caps I’ve found are just short of 20€ a piece, and I’m cheap, so I don’t feel like playing around.
Restuff the caps? Has anybody ever called you a cowboy? 🤠 I guess you could do that from an aesthetic POV, and maybe with enough selastic it would work. But somewhere in the back of my mind I know that it will fail at the worst time, and I’ll have to retrofit some other caps anyway… Only this time it’ll be raining and 2°C when I have to take the inverter apart.
Thanks for the idea of retrofitting. I was so stuck sourcing a drop in replacement that I hadn’t really considered that approach. The real estate is there to take a drill press with a 1mm drill and make a slot for normal snapin connectors. It’ll even maintain the same center, somewhat at least. Time to play with some selastic!
Thanks for all your input, it’s been fantastic. And the ideas thing? Right there with you pal.
For future reference, I found a source for the cap. Turns out that setting your parametric filter to exactly 660uF was the trick. Found chemo-con EKHJ451VSN661MA59M on mouser with a moq of “only” 200@12€… But digikey sells them individually at the same price.
I think I’ve managed to do what you asked, let me know if I messed it up.
I got my function gen to do 6.1-12 in two decades x100 and x1000. The sweeps are almost linear after the first 500ms, meaning that each horizontal division of each 200ms denotes the following:
Well I guess, I’ve got a sweeping function gen and a 4ch DSO… I’m gonna look into that and get back.
Caveat: my engineering diploma in embedded electronics is 10 years old, and it’s been awhile since I’ve done more than just the odd solder job. So it’s going to take a little while.
@gondezee when you say “plot a frequency sweep” what you’re looking for is just the usual voltage/time graph from a scope? No resistance in parallel to the capacitor for discharge? No fixed resistance in series? No x/y graphing funny business?
Or are you looking for a bode plot? I was hesitant in my first response because I thought I remembered Dave doing a bode plot with a sweeping gen and a scope, but I wasn’t sure if I could find it. I could m.youtube.com/watch?v=uMH2hGvqhlE
No output with MCP1700-3302E
I’m trying to build a esp8266 weather station and got some MCP1700-3302E to power the esp8266 from a lipo. But when I connect the lipo to the MCP1700 (looking at it flat spot at the front, ground left, Vin in the middle and Vout on the right) I get no output at Vout. I googled and could not find anything. I tested 5 different...
Calibrating vintage multimeter
I’ve recently acquired an uncalibrated Philips PM2534 (edit: the battery-backed factory calibration data was lost due to the battery running out). I’m looking into somehow getting it calibrated. However, the calibration procedure is rather involved, and requires such things as an exact 300V DC (the service manual recommends...
SOLVED. Identification of angled snapin terminals on AC inverter filter cap (sh.itjust.works)
Solution: @DJPhil has made some really insightful comments below, which are really useful. If you just want the cap you can set the parametric searches for 660uF, or in September 2023 I’ve found that digikey stock(s/ed) chemi-con EKHJ451VSN661MA59M....
Worlds largest brain bank contains 10000 brains (www.bbc.com)
The video shows brains, but no blood....
How do you determine if 450V caps are in spec?
Questions:...