Enchanted Objects Design Challenge - Turn on and offable

RE: Enchanted Objects Design Challenge - Turn on and offable

crjeder — Fri, 12 Jun 2015 06:11:38 GMT

That's exactly the things I have no clue of: the magic tossing of resistors and capacitos around ICs and other active components. So thanks for sharing your insights!

RE: Enchanted Objects Design Challenge - Turn on and offable

Workshopshed — Wed, 10 Jun 2015 21:26:07 GMT

I put a little cross over on the stripboard with cut tracks underneath. I remade the cable (the housings were a bit battered). Much happier with the results. Thanks for convincing me to make the change [mention:8fb233e8974445138ef0af2b63b49f94:e9ed411860ed4f2ba0265705b8793d05]

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shabaz I've some yellow nail varnish left over from a different project so I'll use that for marking up the connectors.

RE: Enchanted Objects Design Challenge - Turn on and offable

DAB — Wed, 10 Jun 2015 19:11:39 GMT

Nice update Andy.

I like the simple circuit approach.

DAB

RE: Enchanted Objects Design Challenge - Turn on and offable

mcb1 — Wed, 10 Jun 2015 11:36:36 GMT

The gate capacitance is pF.

It's really only a problem when you're trying to switch it fast.

You could easily drop the series resistor to a few ohms and be totally safe.

Also the spec says the gate voltage ranges from 2v to 4v, and the load current is quite low.

The IRF540 includes a flyback diode so the extra one is not needed ...however it is good design practice.

I'd be tending to use a spot of hot glue on one end of that crossover type lead ...I can see magic smoke ..

Mark

RE: Enchanted Objects Design Challenge - Turn on and offable

shabaz — Wed, 10 Jun 2015 11:07:28 GMT

Hi Andy,

Like you, I too use non-polarized (i.e. cheap!) connectors for prototypes, one trick (well, an obvious one, I'm sure you know it) to help with connector orientation is to put a blob of marker paint on the board and/or the connector.

Ambersil paint in a penAmbersil paint in a pen is quite good, it dries to a bright finish even against black connectors.

RE: Enchanted Objects Design Challenge - Turn on and offable

balearicdynamics — Wed, 10 Jun 2015 09:03:50 GMT

Interesting explanation. You have just answered to a couple of doubt I had with a very similar circuit (usinga transistor instead of the mosfet) but the principle is exactly the same.