Tools needed.

[Harry Bissell]

Good point Glen:

The Lissajous (X-Y) display is a really good method.  I do it this way, and use
the
chromatic tuner to make sure the reference does not drift.  You can tell
directly from
the X-Y if the frequency is 2:1, or 4:1.  But it is NOT easy to do it this way
and you
need to count very carefully.

I have never found the frequency counter useful except for sanity checks. Mine
broke
a long time ago (batteries are dead).  I better fix it before NiCad batteries
become
TOTALLY non available.

H^) harry

Glen wrote:

> 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