Introduction: Simple DC A-meter

I got idea when I was doing something with DC motors. I wanted to check the current but I was beginning to get angry on digital instrument. So I created DC A-meter that can measure up to 5 A.

This A-meter is very simple. The question is if it can be useful at all? YES! Most cheap digital instruments must not be connected more than 10s in the circuit when we are measuring more than 1 A, but this kind of instrument can be.

All the materials are scraps from other projects (including A-meter).

Spends: 0$
Used-up time: 1 hour

Step 1: Parts in Tools

Parts used for A-meter:
- Analogue DC A-meter
- 1x black connector
- 1x red connector
- 2x cable boots
- housing

Tools used in process:
- Pen
- Driller
- Saw
- Pliers
- Knife
- 2 mm and 8 mm drill

Step 2: Cutting and Drilling

First I draw sketch of A-meter on housing. Housing had some holes from some old projects.

After sketching, I cut out large hole. I used saw for wood. When I was finished, I had removed all the rough edges with knife. When the large hole was finished, I placed A-meter into hole. I did rough sketch where holes for screw should be. Then I drilled for holes with 2 mm drill.

Holes for connectors were already cut. I just needed to make it bigger so the connectors can fit in. I did that with 8 mm drill.

In the end of this step I fit in A-meter and both connectors.

Step 3: Wiring

I have some wires attached to the A-meter. Because I was in hurry I didn’t change them. Those wires are around 0.75 mm^2. This mean that they can still be good for 5 A at 24 V. So I didn’t bother.

I shorted these wires to right length and then I have attached cable boots. After that I bolted cable boots on connectors. For these actions I used pliers.

Step 4: Finish It Up

When all parts were properly installed, I close the housing. I use acryl mixture to cover left over holes.

And there you have DC A-meter that can measure up to 5A!  =)

Step 5: Testing

For testing I have used DC driller. I measured around 200 mA. For comparison, with cheap digital instrument I measured 0.23 A, which is 230 mA. When we compare those two instruments we must count in classes of instruments and that analogue instruments is accurate in the last third of his range.

 

It is not perfect, but for me that is fair enough!

Comments

author
Phil B (author)2012-05-03

Have you given any thought to adding resistor shunts for reading the current draw on other applications? I know that would require working out the calibrations for various shunt resistances.

author
vonPongrac (author)Phil B2012-05-03

That is actualy a good idea! I never tought of that. I think calibrations will be less of a problem if I use mu*tisim or other simulator. But for now this instrument is working great. :)

author
Phil B (author)vonPongrac2012-05-04

When I commented I realized you had a specific application and it was already within the ranger of your current meter display. Thank you.

About This Instructable

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Bio: I am an engineer and a maker who loves technology challenges.
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