Will this work because it says it only goes to 20V/20A...maybe I could have one for each mosfet, but then wouldn't the 20V limit me from using it on the 24V set up (also I need to measure up to 50 amps)? I do have a little meter I use for measuring current that will go up to something rediculous like well over 100 amps that I was going to just run inline with the DUT to measure the total current, however, since this item is so cheap I might just use it as more of a permenant fixture (if it will work).
What about this one (it's 50V200A - they have one that is 100A but the shipping is $10 more):
**broken link removed**
Oh! Yeah... Yours is better to be sure. ONCE AGAIN, I totally forgot we were aiming for 24v. We could have used a voltage divider with the other one, so the meter was reading some easy to calculate fraction of input voltage. And I doubt that you're going to actually see 100% of your 24v on our load, since loading the line will cause it to drop considerably. So the other meter could have worked. But a meter that covers the full range and then some from the start is a far better choice, obviously. Note that that meter is shipped from Hong-Kong and has a 16-28 business days delivery wait. If you want it at all, I would order it now.
As for current limit, I found this in the listing, which is why it can do ~100A....
Ebay said:
IMPORTANT : A 100A 75mV Shunt [sense resistor](not included, available in our store) must be added if the meter is used to measure current / amps; otherwise the meter will be damaged.
This is normal. To measure current, generally you must first turn it into a voltage. As you're no doubt aware, we do this with a physically large sense resistor. Well... those meters couldn't have something like that built in. This is why you have to buy that separately. It's unfortunate that it doesn't come with one. But they would have to make the price higher if it did.
For our current sense, We were going to go a similar rout to what the above meter uses. We use a sense resistor, but the voltage we get from such sense resistor is very small. So small that we almost certainly will have to amplify it to some extent. We would feed this amplified VOLTAGE into a VOLTAGE meter to get a read out. We would have to indicate to our selves that we were looking at Amps, not volts. But the meter would be seeing volts. This is normally the way you do current measurement, and was the plan all along. Things will probably be set up so we have a current/voltage switch and one unmarked meter. Then you just have to know which your looking at for a given time.
The above meter works the same way as our original plan, so we will still be using that configuration to some extent. Chances are, the button on the front of that meter just changes between two different voltage measuring channels, one amplified for current measurement and one divided for voltages. If so, we don't even have to use the button and could make our own switch for such things. Not that there is a good reason to do that.
Anyway, I have to repair laptops today, to make money for bills and such. I'll be back on this some time soon.