Multimeter Mini-Tutorial

[DrNomis_44]

Hi everyone, just as a little addendum to my Multimeter Mini-Tutorial, if you have an Analogue Needle-style Multimeter, here's the procedure you need to follow before you do a resistance measurement:


Assuming that the meter has a good fresh battery installed:


1, Switch the meter to an appropriate resistance range, X1 or X10 is a good choice if you are doing continuity checks.

2, Touch the tips of the two meter probes together, the meter needle will swing to the right towards the Zero-mark on the meter scale, it may also come to a stop before or after the Zero-mark.

3, Next, rotate the Zero-Adjust knob one way or the other to get the meter needle to sit right over the Zero-mark on the meter scale, this compensates for the small amount of resistance that the meter leads contribute to the resistance reading, it also compensates for the battery gradually going flat too.

4, Proceed to doing the continuity checks, continuity will be indicated by the meter needle coming to a rest near the zero-mark.

[corsair]

This community is just brilliant, I have to say... I know how to use a DMM but seeing this is great as there are many out there who are unsure of exactly how to use one! I have a pro quality job out in my tech tools drawer but there is a basic Dick Smith one in the junk/tool drawer in the kitchen that everyone in the family knows how to use to check DC battery voltages and continuity in basic circuits, and yes... they all know not to stick the probes into power sockets!! :-)

Thanks to DrNomis for putting this up!!

[DrNomis_44]

This community is just brilliant, I have to say... I know how to use a DMM but seeing this is great as there are many out there who are unsure of exactly how to use one! I have a pro quality job out in my tech tools drawer but there is a basic Dick Smith one in the junk/tool drawer in the kitchen that everyone in the family knows how to use to check DC battery voltages and continuity in basic circuits, and yes... they all know not to stick the probes into power sockets!! :-)

Thanks to DrNomis for putting this up!!

You are most welcome.

[Simon Barden]

Some multimeters (again, not expensive ones) also have a capacitance testing mode. Useful if you have a selection of similar value capacitors but want to find one that's closest to the value you need. A lot of the cheaper capacitors have a ±20% manufacturing tolerance, and even more expensive ones are ±10%, so if you want to fit one to a tone control circuit and have bought a pack of 10, then it's worth testing them all out and using the one closest to your design value.

Meters with this function have a couple of slots to stick the capacitor legs in. They have spring contacts inside the slots, so they will hold the capacitor in place (though you may have to bend the capacitor's legs to fit). Again, unless you have an expensive auto-ranging capacitor, you'll need to select the correct capacitance range on the meter, so it's best to make sure you're familiar with milli-, micro-, nano- and pico- farad terminologies (mF, μF, nF and pF) and equivalent values e.g. 0.022 microfarads is the same as 22 nanofarads.

With all but electrolytic capacitors (tubular shaped ones, normally with a line of "+++++" on one side to indicate the +ve connection leg) it doesn't matter what way round you stick them in. Electrolytics aren't normally used in tone circuits but if you do ever need to test one for something else, just make sure the +ve leg goes into the +ve slot to get a correct reading.

[DrNomis_44]

Some multimeters (again, not expensive ones) also have a capacitance testing mode. Useful if you have a selection of similar value capacitors but want to find one that's closest to the value you need. A lot of the cheaper capacitors have a ±20% manufacturing tolerance, and even more expensive ones are ±10%, so if you want to fit one to a tone control circuit and have bought a pack of 10, then it's worth testing them all out and using the one closest to your design value.

Meters with this function have a couple of slots to stick the capacitor legs in. They have spring contacts inside the slots, so they will hold the capacitor in place (though you may have to bend the capacitor's legs to fit). Again, unless you have an expensive auto-ranging capacitor, you'll need to select the correct capacitance range on the meter, so it's best to make sure you're familiar with milli-, micro-, nano- and pico- farad terminologies (mF, μF, nF and pF) and equivalent values e.g. 0.022 microfarads is the same as 22 nanofarads.

With all but electrolytic capacitors (tubular shaped ones, normally with a line of "+++++" on one side to indicate the +ve connection leg) it doesn't matter what way round you stick them in. Electrolytics aren't normally used in tone circuits but if you do ever need to test one for something else, just make sure the +ve leg goes into the +ve slot to get a correct reading.

Cheers for that, I bought a Digital Multimeter from Dick Smith Electronics a few years ago, which also included an Inductance measuring function as well as Capacitance and Frequency, it cost me about $99.00, but it stopped working so I have been looking for a good replacement that offered the same range of functions.

[Simon Barden]

Mine wasn't expensive, maybe £25/A$42. I can no longer find it on the web site of the store I got it from maybe 2 years ago, Maplin, (our equivalent of Jaycar) but they have ones with similar functions, for a similar price (Jaycar seem to have similar looking meters for similar prices). I find they often have them marked down in sales.

[DrNomis_44]

Mine wasn't expensive, maybe £25/A$42. I can no longer find it on the web site of the store I got it from maybe 2 years ago, Maplin, (our equivalent of Jaycar) but they have ones with similar functions, for a similar price (Jaycar seem to have similar looking meters for similar prices). I find they often have them marked down in sales.

I also have a 25Mhz Dual Trace Oscilloscope which I sometimes use to trace out signals in one of my Pedal builds, I bought it new from Dick Smith Electronics back in the late 90's, back then, it cost me around $700.00 or so, it's a great bit of test gear, I also have a small single-trace 10Mhz Oscilloscope, next year I'm going to look at buying a new Digital Oscilloscope , and I'll also start ordering some new components for a Soldano SLO 50 amp head I'm going to be working on, the chassis is currently sitting on top of my Marshall amp, it uses five 12AX7 twin-triodes, and two EL34 power pentodes, should sound pretty cool once it's finished and working.