Measuring current draw of pedals

[sfr]

Working on the second half of my all-in one unit, (I guess it's an all-in-two unit now, I split it in half)  I went out to measure the current draw of all the pedals in that are to be included in this one.  Three pedals in this box, the A/DA flanger clone, a PT-80 delay, and a Tremulus lune.  Might stick one more in there, I don't know. 

Since the PT-80 and the A/DA both run off of 18V, I hooked the Tremulus Lune up to a 9V voltage regulator, the idea being I can run just one power supply to the box.  Searching for a suitable 18V adaptor, I find myself wishing there was an 18V 1Spot.  The 18V supply I have now are the 18V taps on my Gator G-Bus, which is nice but involves three cables; I'd like to just bring one wallwart. 

So anyway, trying to figure out current consumption so I have something that can power these - using my breadboard, I hook up the -/ground power connection between the power supply and the pedal, and then connect the red lead of my meter (set to read current) to the power supplies + lead, and the black lead of the meter to the + power connection on the pedal.  I get a number, but they seem suspiciously low ...   And none of the lights will turn on. I know when I measured my 9V pedals (using a battery rather than a powersupply) the LEDs would turn on.   

Just hooking the power supply up to the pedal works.  Putting the meter in-line with the + and nothing.  Is this likely a side effect of the voltage regulators in the pedal circuits?  Of my power supply? Or am I (more likely) doing something wrong? 

I'll try again when I get another battery . . . but in the meantime, any advice would help.

[R.G.]

I hate to admit this, but on my meter, there is a different socket for the red lead for current measurements than for voltage measurements. I once puzzled over this for several minutes before finding the clearly marked current sockets. It still catches me sometimes.

I don't know about your meter, but it's worth checking for a different socket for the red lead in current measurement.

[birt]

most meters have the extra red lead socket for current measurement





this one is different:

[GibsonGM]

Right...there can also be a jack for up to "500mA", for example, and a 2nd for "10A Max".  A little something to consider if you're measuring current at line voltage etc. 

If you have everything connected correctly, the meter scale set right, and you still get nada, I might get suspicious of having blown a fuse inside the meter....

[puretube]

which can happen, when you forget to put the lead back into the other socket, when you want to measure voltages, next...   

[Seljer]

which can happen, when you forget to put the lead back into the other socket, when you want to measure voltages, next...   

I did that a while ago when experimenting with the electrolysis etching  , didn't notice the "fuse 200mA max". But it still measures voltages, it just cant measure current

[sfr]

Okay, color me embarrased.   

Yeah, that's it.  I guess it's what I get for working on projects when I'm too sleepy.  I've done current measurements with this meter before, so I should know this; I don't know how I managed to forget this time. 

Thanks guys. 

[R.G.]

Happens to us all.

Well, OK, me at least... over and over. 

[GibsonGM]

Don't feel bad, I still look at my resistor color code chart, even tho I know "BBROYGBVGW" and their values.  Retardation sets in after 6 hours with the soldering iron... 

[mac]

And sometimes you simply forget to power up the circuit...

mac

[rogeryu_ph]

Hi to everyone on this thread... I'm interested in your topic and I have a little knowledge on electronic also I have a DMM I could use, could you give me a simple instructions or guide  on how to measure the current draw of a single 9v pedal... Anyone... Thanks guys in advance.

[R.G.]

Open the pedal up, move the battery clip to where you can access it easily.

Remove the battery from the clip.

Plug ONE of the battery clip contacts onto its matching contact on the battery by turning the clip sideways to the battery. Leave the clip turned at right angles to the battery.

Turn the effect power on - by its power switch or by inserting a cable into a jack.

Take your DMM and plug the +/red lead connected into one of the current measuring sockets, Turn the selector switch turned to a current range, something under 100ma and over a couple of ma.

Clip one DMM lead to the unconnected battery contact. Connect the other to the unconnected battery clip contact.

Now switch the bypass in and out. If the pedal has an indicator LED, you should see current increase when the LED comes on.

Read the number of ma from the meter.

[Processaurus]

I made this contraption for an easy way to check current consumption in pedals that work off 2.1mm DC power supplies, its been handy...

[Short Circuit]

which can happen, when you forget to put the lead back into the other socket, when you want to measure voltages, next...   

I did that a while ago when experimenting with the electrolysis etching  , didn't notice the "fuse 200mA max". But it still measures voltages, it just cant measure current

If you take your meter apart there should be a fuse inside there that is blown. Replace that fuse and the current measurement should work again.

Mark

[rogeryu_ph]

Thanks  RG,
Correct me if  I got the idea.. Only one(1) supply line either neg or pos to be break and I will insert the test prog between and then switch on to get the current?

[R.G.]

Yes - you are correct. Break only one side, measure current in that side.

[runmikeyrun]

my electricity teacher taught us this to remember resistor color codes:

Bad
Boys
Rape
Our
Young
Girls
But
Violet
Gives
Willingly