[sdiy] Useful equipment

Byron G. Jacquot thescum at surfree.com
Fri Aug 2 18:39:53 CEST 2002


>I'd really appreciate it if somebody could go over the list and tell me
which things I need, which I don't, and which have cheaper or more readily
available equivalents that I could substitute.

OK, here goes.  I'll comment on your list, based on what's on my workbench,
which has turned out a a few DIY projects, and a fair bit of musical repair
& hotrodding work.  There are a lot of bargains to be had on test gear these
days...keep an eye towards Ebay, ham radio swapmeets, and any local
electronic surplus shops.

>Scope:
>Tektronix 2225 Dual channel, 50 MHz 

A scope is probably one of the most useful things you can have on your
bench.  The specs needed for synth DIY work are probably lower than those
for general electronics work...if you're got going to repair TVs or radios
or computer systems on the side, then you don't need so much bandwidth, or
lots of channels.

Tektronix, HP, B&K and others all have made decent scopes.  I use a dual
channel B&K 10MHz scope, which has never given me any troubles, and is
suffucuent for what I do.

>Func. Gen.
>Krohn-Hite 1400 sine, triangle, square, logic level; sweep; tp 3MHz

Sometimes you need to be able to generate a tone to test out your circuits
with, and a function generator will do that.  I've got a very simple one,
made from a kit, with square and triangle outputs.  IT's not fancy, or
calibrated, but when I need to run a tone to check a signal path, it does
fine.  I think the kit was about $10, and the box to stick it in was $15!

>DVM
>Beckman DM25L 3 1/2 Digit
>
>VOM
>Simpson 260-8P multimeter with overload protection (essential!)

I've only got a single meter on my bench, a fairly cheap 3 1/2 digit
multimeter.  It does volts, current, resistance, capicitance, and has diode
and transistor checkers, a frequency counter and temperaturwe probe.  It's
functional, but there are times that I wish for more resolution in the
measurements.

Nearly any simple DVM will get you started, bit you'll probably want
something better (like a Fluke) one day.

>Power Supply
>B&K Precision 1630 0-30v, 3A linear

For synth work, we're usually using fixed +/-15V, with .25A being enough for
many smaller projects.  I tend to put a new supply in each project, rather
than having a bench supply.  As has been mentioned on the list before, there
are some good linear bipolar 15V supplies that can be found on the surplus
market.  Lambda and Power One are a couple names to watch for.

>Breadboard (Powered)
>Global Specialties PB503 3 supplies (+5V, +/-15V), function generator
including logic level; debounced switches, 8 LED indicators
>Breadboards, not powered
>Global PB-105 set of six strips, mounted
>Global UBS-100 single strip (beware of cheap imitations.)

Breadboards are a point of contention among electronics hobbiests.  They can
cause problems with some circuits because of the stray capacitance between
the strips.  Cheap breadboards are even worse, becauee they not only bring
that capacitance, the connections become intermittent quickly.  I've got one
akin to the powered one mentioned, and it's handy when prototyping my own
circuits.  If you're going to start from kits, before designing your own
circuits, this can wait a while.  It's often handy just for the switches,
power supply and function generator, wired into projects built on stripboard.

>Logic Probe
>OK PRB50 O,K IndustriesL 50 ns glitch
>or HP545A

If you're doing digital circuits, a logic probe can be handy.  A lot of the
same ground can be covered by a scope or DVM.  If you're doing enough
digital work that your logic probe gets a lot of work, you're probably going
to want a logic analyzer.

>Resistor Substitution Box RD111 (contact easy) 1ohm to 11Mohm in 1ohm
steps; +/- 1%
>or ohmite ohm-ranger 3420.
>Capacitor Substitution Box
>Ohmite 3430A Cap-Ranger
>100pF to 11.111 uF in 100pF steps; +/- 2% accuracy.

I don't have either of these...a handful of caps and resistors can be used,
though it might be a little more work to solder and desolder when experimenting.

>Resistor Kit
>Ohmite CAB-54 "little devil" 1/4 watt carbon composition; 10ohm to 10Mohm

Lots of folks carry resistor kits.  1/4 watt is suitable for most solid
state DIY work, if you can find one with metal film resistors, they're a
little less noisy than the carbon ones.  

Get one that comes in the cabinet, sorted by resistor value.  It's expensive
up front, but worth it in the long run.  As you use up the resistors that
came with it, you can refill the compartments with bags of 100 or 200
resistors down the road...if figure that if I've used enough 10K resistors
to deplete the 40 or so from the kit, then I'll probably also use up a bag
of 100.

>also it says
>(your choice)
>a frequency counter: occasionally very helpful.

For musical work, a frequency counter is pretty handy...spend the few extra
bucks to get a DVM with on in it, and you'll be OK.

Byron Jacquot




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