Is there -12v conversion on H5?

[Steve]

Ok thanks

[exxos]

You can also "roll your own" with off the shelf parts.. You would need those negative voltage regulators if you want -5V as well.

https://theorycircuit.com/negative-volt ... r-circuit/

negative-voltage-generator-circuit-using-555.png

Basically when the 555 output is high, C4 charges up though D1 (gnd basically). Nothing new there. But when the output goes to gnd, the capacitor has about 12V across it still. So as positive of the capacitor is now connector to gnd (via the 555) the other side of the capacitor has to go -12V negative. D2 blocks the positive output from the 555 from being fed into the negative output.

Wrote "off the top of my head" but probably better explanations on the net.

[Steve]

@exxos

Just reviving my thread as I'm still dealing with this, I bought a MAX635 inverting regulator:
https://www.mouser.co.uk/datasheet/2/25 ... 292650.pdf

I'll attempt to build a circuit where I put 12v in and get -12v out, I noticed on the datasheet it says I'd need a 470uh inductor for the circuit, but it also says 0.88 Ohms for the inductor. I did some googling and apparently Henries are completely different to Ohms, can I safely ignore what it says about the Ohms on the datasheet?

I was thinking of getting the 1W 470uh from: https://www.ebay.co.uk/itm/263867106353 - would you say this would suffice? Thanks

[exxos]

Should work. I mean is not exactly a powerful chip pushing something like 40mA anyway, approx 500mW. But I don't know how much your going to be pulling anyway ?

Might be worth looking for a bobbin inductor like the suggested parts. The smaller they are the easier they saturate and lower the value becomes. You may have something like a 470uH inductor rated for the power you need, but at 20mA it would be more like 200uH. A bit more current and inductor acts like a short circuit and blows up anything which is attached to it. One of my pet hates is almost nobody seems to know what inductor saturation is, will resist the 20 pages rant for now ;)

Resistance of the inductor is more related to efficiency and how hot the things get. Lower is of course always more preferable. Again it also depends on how much current you are going to be pulling, as higher resistance values may cause such a efficiency loss that it may not be able to deliver full output current.

So you may be okay for something like 10mA with that part. But I would honestly just look for something more compatible of what is listed on the datasheet. IE bobbin type.