Ammeters/Voltmeters

judygee · Post by **judygee** » 20 Jul 2006, 10:51

HELP!! How do you good people stop students from blowing the wires in Ammeters/Voltmeters etc. I guess you can have them repaired but where does one go for that? Can it be done by a handy man with the correct wire? Where does one get the correct wire or is it a matter of a Fuse? Would it be cheaper to buy new ones? Your input would be appreciated. Thanks. Judygee

Post by **Ocker** » 20 Jul 2006, 11:42

The best methord is have the teacher check the kids circuit before they are allowed to turn on!
Replace the meters with digital multimeters that are overload protected but this can be a problem sometimes when values are not steady, you can see a needle pointer wavering but the digital meter will not settle on a reading.
Some meters have a hold button that samples the reading at afrozen moment in time.
The digital meters are a lot more accurate and half the price of analogue meters.

tania · Post by **tania** » 20 Jul 2006, 14:20

I have found them very tricky to repair.
You can purchase the wires from Dick Smith, than you need to solder in the wires at the correct length without over heating the circuit.
Scientrific offers repairs, or go to http://www.rtg.wa.edu.au for a guide to repairs.
Tania

judygee · Post by **judygee** » 25 Jul 2006, 09:43

Thanks for your input Ocker and Tania - think I will have to go with the multimeter idea, replacing the wire does'nt appear to be a simple as I thought and stopping the students from burning out the meters seems to be practically impossible to achieve even with teacher cooperation! Once again - thanks. judygee.

Post by **Ocker** » 25 Jul 2006, 11:56

If you decide to buy multimeters I have found best prices are at Jaycar od Dick Smith but remember to get overload protected or the kids will blow them also be aware that some have to be turned off or they flatten battery, others turn themselves off after 5 min with no reading when measuring high currents you usually have to change input hole of one lead.
I purchased the ones with hold button, and often have students saying "this is not working" but press hold button again and all is fine.
When you get familure with the multimeters you would never go back so take the time to get familure with them

rp · Post by rp » 25 Jul 2006, 14:33

there is a maintenance company that go around the schools and fix broken equipment.I have a big box of stuff to fix but havent quite had the time to book them.
I will try and get details later if I can

Robbie · Post by **Robbie** » 31 Jul 2006, 12:43

John Reed of Broken Bay Communications will come to schools and repair most equipment (except microscopes). His phone number is (02) 9918 2911, mobile 0407 498 520. I am not sure how far he is prepared to travel. We have used his services many times over the years.

Robyn

lada · Post by **lada** » 01 Aug 2006, 14:43

yes, we too have used John Reed in past. Well worth doing, he will save you heaps, plus no need to get new equipment. Lada

PhysicsOne · Post by **PhysicsOne** » 03 Aug 2006, 13:27

Ammeters have protection diodes that can burn out when they get too much current. Replacing these usually fixes most of them. Ammeters also have shunts to give different ranges of amps.
Voltmeters have resistors for the different voltage ranges.
If you know how to use a multimeter you can check and replace the broken components.

If you don't have time or not sure send them for repair as stated earlier.

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