Inline Pedalboard Meter

[karbomusic]

So I had this little raw volt/ammeter thingy I bought a few months ago. It dawned on me that what I could really use is this married together with a 1590A into an inline meter circuit for my pedal board and testing circuits in general. It has it's own separate power supply to power the measurements and all you do is slip that inline with the main pedal supply:



I hope that wasn't a bad idea, seems to work well enough. It is showing >170mA because every pedal on the board is on and I was wanting to get a baseline of the consumption etc.

[armdnrdy]

You know....I tried putting together a basic current draw ammeter box for my bench to measure each pedal types current draw...

I used a modular unit such as what is depicted in your photo.

Depending on the pedal...the accuracy varied!

I would check the current draw with my Fluke 87 (which I trust as being accurate) and I would check with the modular ammeter...
the current readings would vary greatly.

I tried three different types of ammeters with varying results....I finally gave up on the ammeter displays and built a box with binding posts for use with my Fluke.

Have you checked the readings from your pedalboard meter with an accurate DMM?

[karbomusic]

I didn't measure per pedal but initial tests seemed OK against my other meters. It doesn't need to be dead accurate for what I'm using it for though, I mean way off would be a problem but the main use was "Is my voltage dropping and/or am I about to melt my PSU". 

[armdnrdy]

I'm talking about some of the single pedals being off 5ma!

That's a substantial discrepancy!

[karbomusic]

It is but not for what I'm needing this to be used for. I have a 1.6 amp PSU (apparently overkill), I just need to make sure all pedals running full tilt don't exceed that and that my voltage stays steady. But as I see pedals going on and off it appears to change according to the original individual readings on the breadboard when building (aka 5mA whathaveyou). I'm sure it could use some calibration, just haven't gotten that far yet.

For actual breadboard stuff while I'm building I use my calibrated meters.

[armdnrdy]

Do you have a link to the meter display that you used?....maybe I'll give that one a try.

[karbomusic]

Do you have a link to the meter display that you used?....maybe I'll give that one a try.

That's a good question actually. I'll try to look when I get home and reply back as it's been lying around for a couple months (watch it be a mile off and make me look silly lol). I "think" there was the possibility of some calibration but don't quote me because I purchased that and a voltmeter and the details are beginning to blur. I should correct my misspoken part that for testing it wasn't for mission critical stuff so I don't want to give the impression that I use this for the same things you described. It was more for "Does my sound, sound funny because of power" at a gig type of sanity check, that and making sure I'm not exceeding the limits on my PSUs. Does anyone else smell smoke?

[armdnrdy]

I realize that we are using the meter for two different things.

Yours more for overall pedal board reference, mine...I want a reading so that I can put a fairly accurate current draw number to each pedal.

As it stands right now...I just guesstimate.

[karbomusic]

I realize that we are using the meter for two different things.

Yours more for overall pedal board reference, mine...I want a reading so that I can put a fairly accurate current draw number to each pedal.

As it stands right now...I just guesstimate.

Understood, when I get a chance actually measure to see what discrepancy is there as well and reply.

[karbomusic]

@Larry

Just following up as promised. With the equipment that I have to test with:

Digilent Analog Explorer. That is a wonderful piece of gear btw.
Milwaukee 2216-20

It shows as exact as I know how to measure. I'd say from the few tests I did the variance is about a 1mA using various circuits I had on breadboards, some LEDs I had lying around and a pedal or two. I had to settle with that number since the circuits themselves sway by at least 1mA. I'm sure I could find something wrong with it but those few tests were spot on best I could tell which to be honest I didn't expect to find. That is based on powering the unit with a separate 9V supply. There are instructions on how to calibrate it to use the unit under test as the PSU but I built it so that the unit under test is isolated from the powering of the unit itself. I could be missing something though since I don't have anything actually NIST certified here.

This is the exact unit I have, hope this helps.