Change Analog Ameter Range - Page 1
Forum section: electronics / beginners

author: EpicIntelGamer
author_rank: Regular Contributor
timestamp: August 03, 2013, 10:16:40 pm
content: Hello!I have a few panelmount analog DC 10amp ammeters and I was wondering if there was a way that I could make them maybe go from 0 to 1 amp instead of 0 to 10amps.Thanks!

author: Bored@Work
author_rank: Super Contributor
timestamp: August 03, 2013, 10:44:02 pm
content: Find the shunt resistor, replace it.

author: EpicIntelGamer
author_rank: Regular Contributor
timestamp: August 03, 2013, 11:05:48 pm
content: Quote from: Bored@Work on August 03, 2013, 10:44:02 pmI just ripped apar the meter and I don't see any resistors. Just looks like a big piece of wire wrapped around some plastic with a needle on a pin in the middle of that coil.

author: David_AVD
author_rank: Super Contributor
timestamp: August 03, 2013, 11:22:24 pm
content: Some current meters have the shunt internally, while others have it externally. It is in parallel with the two meter terminals and can look like a steel bar. Maybe you removed it already? Have you used it to measure current yet?

author: EpicIntelGamer
author_rank: Regular Contributor
timestamp: August 03, 2013, 11:40:44 pm
content: Quote from: David_AVD on August 03, 2013, 11:22:24 pmI've used this meter before, it works great. Really though there is nothing more in here than a coil. And to prove it, I wrapped a bit of wire around that plastic part and just connected it up in series with a load and the needle did move.

author: EpicIntelGamer
author_rank: Regular Contributor
timestamp: August 03, 2013, 11:43:42 pm
content: Here's some pics!

author: IanB
author_rank: Super Contributor
timestamp: August 03, 2013, 11:44:31 pm
content: Some 10 amp meters may be moving magnet meters, rather than moving coil meters. They may not have a shunt.

author: IanB
author_rank: Super Contributor
timestamp: August 03, 2013, 11:45:40 pm
content: Quote from: EpicIntelGamer on August 03, 2013, 11:43:42 pmYup, those are 10 A meters. They don't have a shunt, and you can't alter them. They are what they are.

author: David_AVD
author_rank: Super Contributor
timestamp: August 03, 2013, 11:51:16 pm
content: I've not seen one like that. You learn something new every day!

author: onlooker
author_rank: Frequent Contributor
timestamp: August 04, 2013, 12:08:03 am
content: The construction looks so simple; You may just rewind it with 10 times the turns (with thinner wire to fit in to the same space).

author: c4757p
author_rank: Super Contributor
timestamp: August 04, 2013, 12:19:01 am
content: Sounds like a good solution.

author: EpicIntelGamer
author_rank: Regular Contributor
timestamp: August 04, 2013, 03:15:49 am
content: I removed the old coil and put on 15 turns of some smaller wire and the meter was going way off the guage with only 1.5a load.I actually found out this is because I moved a magnet that was on the back of the coil assembly.I ended up going with 5 turns (like the original coil) of wire made of the smaller wire (~26AWG or so) and messed around with the magnet as well as the magnet on the 0 adjust screw and got it to a point im happy with.It only uses about half of the meter but it works out okay because about half way is about 2 amps so I'm good with it. It didn't need to be very precise but just a little indicator that I plan to use on my Homemade Bench Power Supply V2.While I'm here and have 2 more of these meters to spare, how hard is it to turn one from DCA to DCV???

author: G7PSK
author_rank: Super Contributor
timestamp: August 04, 2013, 08:56:38 am
content: That looks like a moving iron meter. The only way to alter the readings would be to change the return springs or rewind the coil. The trouble with moving iron meters is that they are not very accurate especially at low currents, but they do have the advantage of being very robust. Should really be called an indicator rather than a meter.