~ Folk Fuzz Group Build Construction Thread ~

[BJF]

All the EL's are 16 or 25 v. I actually wonder if it could be the volume pot--I used one I already had, recycled from a failed project.

Hi,

Elkos should be just fine if you run 9V's. Yes, actually it could be the Volumepot as you describe it.

BJ

[Jagattack]

Can anyone give me any advice on what multimeter to buy?
Yeah I probably don't really need it for the fuzz build, but several times over recent months I have said "I need a DMM" so I want to get one
for the various little jobs that come up.
I think it will help me with the build as well.

I would think:
No need for true RMS?
Or frequency measuring?
Just AC/DC volts and current, ohms, capacitance and diode test?

There's a nice looking Fluke 77 series 3 on ebay now for $61 (but it will go up I guess).

[BJF]

Hi,

A standard DVM would go a really long way.

Fun to have is a capacitance meter. I bought a Hung Chang some 20 years ago that has a built in capacitancemeter and a good one at that and that's one I use

RMS meter et.c are likely not something used that often if at all unless you do electrical installations. For such work Fluke is recommended

Fluke makes really nice DVM's and if you can get a good deal on e-bay go for it.

Measuring on tube amps you'd need at least 600V isolation-preferably one with the best isolation you can get

However for DVM use for a guitarist and for faultfinding guitarpedal or guitarcables a budget DVM such as can be found sometimes even at gas stations would do excelantly especially as some of those have battery condition tests.

Have fun
BJ

[Jagattack]

Thanks BJ,

The Fluke 77 can actually handle up to 1000 volts but many meters seem to be rated to 600 volts max, and since
I do hope to build a small valve amp one day, I might be better off with the 1000 volt meter.

Although the 77 does not have frequency measurement, but I don't know what this would be used for anyway, is it
necessary in your opinion? Do you have a need for frequency measuring? Also it does not have capacitance.

Cheers
Jag

[BJF]

Hi,

Yes, that's why the Fluke is a good choice if you plan to service or build tube amps: you never know when MAjor Marshall shows up at your doorstep

Frequency measurements in a DVM, well if you can measure you can find something to measure, but also a measurement is useless if it is not correctly applied and correctly measured.

Down the road, you may want an oscilloscope and that's the emperor of audio measurements Oh, you'd like a tonegenerator by then too.......

But let me tell you this the one measuring device I have solved the most complicated to the simplest and the absolute majority of problems with is just a standard DVM rated a 600V though so caution has sometimes been called for.

Try to get one with a diodetester as you then can orient various transitors.This can come in handy when you suspect a junction to be blown.

A transistor can be said to be made of two diodes and in an NPN transistor the anodes would be tied together for the base.
Just making junction measurement base to collector and base to emitter would measure like diodes.
Early transistors could be used in reverse but later finer techniques increased the transistor effect and allowed a better designed base emitter junction to be linear over several decades like from 6mV's to 600mV's in 6mV increaments and so reverse coupling did no longer work.

If you need a transistor tester I would be sure there would be some on line schematics, but you can build more complicated transistor testers that allow leakage measurements backwards through collector to base.

Resistans measurements can be used with power removed to solve various problems and once I fixed a 2x400W amplifier by measuring all components and one multilayer ceramic capacitor was the culprit- it behaved as a low resistans resistor instead of a capacitor and thus made the whole outputstage lay flat to one supplyline- something no solidstate outputstage of this caliber is designed to take for more than a few milliseconds without either blowing the fuse or blowing up.
This just goes to show how resistans faultfinding can be.

Voltage measurements usually turns up problems in a powered circuit, but will require a rough guess of what would be correct voltage if that isn't known.

These are just a few things and there are so many more things that could be told but the DVM and the VOM before that is likely to continue to be one of the most valueble devices to an electronic technician and I would not think you'd regrett getting a nice unit but rather think you'd find loads of uses for it.


Have fun
BJ

[Jagattack]

That's great advice BJ, thanks a lot!
A basic 600v model with capacitance and diode test (plus the usual stuff) will do me for now.

Sure I'd like the "emperor of measuring equipment" (lol) but I realise that I wouldn't know how to use it, or what it was telling me!

[BJF]

Hi,

Yes a good DVM does not go outof fashion anytime soon.

Regarding the Emperor, thos usually come with an instructionfolder and there are also resources on line.

Thta's a hardcore investment, while sometimes one can find used scopes at nice prices, while I'd recommend getting one then close to you so you can see that it works properly.

I also think you will know when you need a scope and why you'd need it........just for fun google oscilloscope instructions and see what one such can do for you.

Be certain once you get the emperor you'd not regrett you did

Still most useful always is a DVM

Have fun
BJ