Amerage Seems Wrong on Ugly Buster

Bill Chennault

All--

My tracked Ugly Buster has one BS2p40 and four BS2 Stamps. When all are running, my multimeter tells me they are drawing 0.14ma. Gee. Can this be correct or do I simply not know how to use the amp meter? It is connected in series between the power supply and the breadboard. All current drawn by the breadboard goes through the amp meter. To me, the BS2p40 should draw 40ma and each stamp should draw 3ma for a total of 40 + 3*4 = 52ma. (Taken from the "Sleep" topic in the IDE Help.)

Other than the LEDs in the optical encoders--which might shut themselves off when 12vdc is no longer present; I dunno--there is nothing being driven by any Stamp.

When all programs have encountered their end statements, the current draw drops to 0.11ma.

I must be doing something wrong with the multimeter. I am using COM and the amperage plug and have the dial set at "20m" (20 milliamps).

Can you tell me what I am doing wrong?

Thanks!

--Bill
ps At 0.14ma running, my 8400maH battery pack will last a LONG time.

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You are what you write.

Bill Chennault

All--

Gee. Maybe I didn't get any replies because no one knew what "amerage" meant! Call it a typo. Call it a mis-spelling. Call it anything you want, but I hope you call it "amperage!"

Merry Christmas!

--Bill

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You are what you write.

PJAllen

OK, here's my Reply --

How're you using that ammeter?· Like in the picture I've attached?
Sorry, but I'm trying to get a base-line here, BC.

[noparse][[/noparse]What's all this "amperage" stuff?]

PS -- You can Edit your Subject title, too.

Bill Chennault

PJ Allen--

Thank you for taking the time to make the simple drawing for this simpleton. It helped.

Yes, that is the way I am connecting things. (The "Stamp BD" is a breadboard with five Stamps, but the power connection is simple and the same.)

I do not know how to edit the subject line, but I will soon learn.

--Bill
ps The previous picture was better. He was one of the greatest character actors on PLANET EARTH. And, many of his lines suited the characteristics of your responses.

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You are what you write.

Dgswaner

....edit your first message to change the subject.

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"A complex design is the sign of an inferior designer." - Jamie Hyneman, Myth Buster

DGSwaner

allanlane5

I strongly suspect your meter is reading in "Amps", not "milli-amps". Wait, did you say you set the meter on the 20 mA setting? It's possible you've blown the fuse in the amp-meter -- depends on how much it's designed to read, I've done this often.

If the BS2's take 40, then 3*4 == 12 + 40 == 52 mA, and a couple of LED's take about 15 each, 80 to 100 mA would not be outrageous. "zero point one-four" Milli-Amps ("0.14 mA") WOULD be kind of unlikely.

Here's an easy test -- unplug the BS2p40, and see how much the reading drops.

Chris Savage

I’m inclined to agree with Allan on there being something wrong with the meter. The value given is 140 mA, but if you’re on the 20 mA range then your meter should say (or at least all mine do) OL/Overload. Some meters have a separate connection for higher current ranges. For example, one of my meters has a jack marked ‘A’ where I connect the probes for current readings and one marked ‘10A’ for that range. The lower ranges are all fuse protected.

Edit: You may not be accounting for slightly additional current draw of the LM2940 regulators (quiescent current) on the OEMs, which won't be as efficient as the ones on the modules (such as the BS2p40).

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Chris Savage
Parallax Tech Support

Bill Chennault

Chris--

Something wrong with my $12.95 meter? Why, that's impossible! [noparse]:)[/noparse]

I will check everything again tomorrow, observing everone's advice, and re-ask the question.

I hope everyone has a Merry Christmas!

--Bill

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You are what you write.