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No output with MCP1700-3302E (lemmy.dbzer0.com)

submitted 2 years ago* (last edited 2 years ago) by Froghut@lemmy.dbzer0.com to c/askelectronics@discuss.tchncs.de

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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 ones and it's the same for all of them. Could I just have a batch of broken ones? Edit: attached a picture of my very simple test setup Edit 2: I just connected three lipo directly to Vin, that seems to work without any problems (at least for a few days now)

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[–] joulethief@compuverse.uk 1 points 2 years ago (1 children)

Unlikely. Have you measured the voltage present at Vin?

[–] Froghut@lemmy.dbzer0.com 1 points 2 years ago (1 children)

Yes, I measured across ground and Vin and it shows ~4V. Across ground and Vout 0V.

[–] joulethief@compuverse.uk 1 points 2 years ago (1 children)

Just to be sure: positive probe on Vin, negative probe on GND, measurement shows no minus sign?

[–] Froghut@lemmy.dbzer0.com 1 points 2 years ago (1 children)

Yes, that's what I did and what it shows. I also attached a picture of my test setup just in case I did something wrong there

[–] joulethief@compuverse.uk 1 points 2 years ago (1 children)

Huh, that's weird. Double checking the part markings would've been my next suggestion, but the picture shows they're correct. Maybe try a 1kOhm load resistor across Vout and GND, though in theory you should be able to see the output voltage without it.

[–] Froghut@lemmy.dbzer0.com 1 points 2 years ago

I tried with the resistor, same thing, 0V. I made two images showing the measurements

[–] flippyfingw@discuss.tchncs.de 1 points 2 years ago

Here's something I've been using in my own esp8266 projects for a while, LiFePo4 18650 cells. Their working voltage range, 2.6 - 3.6, 3.2v typical, makes them perfect for esp chips, and you remove the quiescent drain (though really low for mcp1700). Downsides of LFP being, lower capacity in the same size (energy density), pouch cells are generally not available and LiIon is a far more mature tech, with easy (and cheap tp/tc 4056) charging solutions.