Tools needed.

[Glen]

At 03:35 AM 09/07/2000 , Steve Gray wrote:

>If I am going to go into this DIY synth malarky I have a few questions
>about equipment.  I presume I will need an oscilliscope and frequency
>counter. 

The oscilloscope will be very useful for testing and repairing, but you
might be able to live without a frequency counter. I've been an electronics
technician, specializing in keyboards  for nearly 15 years, and I've never
had to use one yet. On the other hand, a good tuner is very important. I
even use the audio output from a quartz tuner (when it's placed in
reference-tone generator mode), to trigger the sweep on my oscilloscope.
Then, I can "look" at a waveform and tune it without having to hear it.
It's also possible to set up a nice X-Y pattern, using the two signals ran
into separate input channels of the scope, and tune that way. 

(One small note about the triggered sweep tuning technique. It is also
possible to accidently tune a note to a ratio other than 1:1, with respect
to the reference signal, such as 2:3.  If you are not listening to the
audio, this technique is only practical when the note is fairly close to
proper pitch already, and you merely want to "touch it up." The X-Y
technique doesn't suffer from this limitation, and can display the actual
pitch ratio, as well as showing whether the note is in tune. For both
techniques, a condition of "in tune" is indicated by a totally stationary
waveform display. Any rolling or movement indicates a frequency difference.)



> Are there any other peices of vital equipment ?  

Of course a variety of good hand tools come to mind, but I guess you
already know that. 

I would emphasize buying a good soldering iron with interchangeable tips
and heating elements, and not a cheap unit. (Whatever you do, DO NOT use
one of those pistol-shaped, instant-on, high-wattage soldering guns to
assemble delicate synth circuitry! Not only do these get too hot for the
circuitry, but they also have a nasty habit of killing delicate parts
through an electrical field they generate.) Temperature control on the iron
would be nice, but I've managed to live without it so far. Make sure your
iron has a grounded cord, for ESD protection. (For that matter, buy the
anti-ESD version of any tool, when you have a choice. Even my solder sucker
is anti-ESD.) 

Now that I mention it, look into ESD protection. Get at least an anti-ESD
wrist strap, and use it according to the directions. An anti-ESD protective
mat to use on your workbench, and another on the floor, would also be nice,
but there are ways to live without these, especially if you are just
starting out and are on a tight budget. (These large mats can be expensive.)

Don't forget to use some sort of smoke extraction technique while
soldering. Special soldering irons can be bought that automatically suck
solder and flux fumes into a hose and trap the smoke in a special filter.
These are expensive and are meant for production work. I would at least use
a small fan on my workbench to keep the fumes from going straight up my
nose. It is also possible to buy small fans that have special filters,
which will trap the smoke in the filter. This might be affordable for you.
Of course the whole point of this is to prevent you from repeatedly
inhaling lead or flux particles, both of which can be toxic, especially
over a long period of time.

A good, accurate,  digital multimeter should definitely be among your test
equipment. I would only buy specialty meters such as  digital capacitance,
or digital LCR meters, if I found myself actually needing them regularly. I
wouldn't worry about them for now, but they can be useful if you are custom
building certain types of analog circuitry and want to precision match your
components.

A signal generator of some sort would be a good idea. This could even be a
simple battery-powered home made oscillator circuit. You probably don't
need to get one of those expensive function generators.

Speaking of home built gear, do a search on the internet for pages that
tell you how to build some of your own basic test gear. Simple items like a
basic signal generator, or a simple power supply can be easily built
instead of purchased. Anything that makes high-precision measurements, like
a digital multimeter, should be purchased rather than built - unless you
are sure you have an accurate way to calibrate the device yourself.

Last, but not least, don't underestimate the benefits of good lighting,
when assembling or repairing circuitry. You'd be surprised how easy it is
to make tragic mistakes in poor lighting.

(I hope this wasn't too much information.)



>About how much would a second-hand midi control keyboard cost ? 

Depending on your personal needs and tastes, it could be anywhere from
free, to thousands of dollars.  :)

I was given a broken synth once, and the unit still transmitted MIDI info,
even though it's own sounds were dead. So, I ended up with a free MIDI
controller. (That is, until I repaired the keyboard. Now, I have an
inexpensive synth.)


Later,

Glen