Oh yeah, put it on the web site, please!!!
Thanks!
-Chris-
>>> jlarryh@... 01/05/01 03:25PM >>>
OK, I'll give you my take on this.
1. I agree. I have this on my DIY list.
2. -5 to +5 for CV range.
3. Yes you can get the voltage by hooking the pot across the power supply
BUT..... You have to use something large so the current is not excessive
4. Yes, you can limit the range with resistors as you mentioned.
The problem as I see it is that your voltage source is unbuffered and the
source impedance is too high. If your load varies much it will in turn
effect your output voltage. So, you want to buffer your output voltage to
provide an output with a lower impedance. My take on that is to use a
simple op-amp circuit. Since your voltage is static and interaction between
op amps is not critical, you could do the whole thing on one nice little
quad op amp like a TL-074. The circuit would have the one chip, four pots,
four caps, and 12 resistors for 4 voltage sources.
Now, if I was going to all the trouble to do this, I would add one more cool
feature (cost you one jack and one resistor per voltage source. I would add
inputs to a couple of the channels. That way you could use it as a stand
along DC source, or to offset / bias / invert some other AC or DC signal.
I just purchased some very nice small protoboards for $1.95 each that would
be perfect for this job. Any other interest? If so I will put it on my web
site. Otherwise I will just send the schematic to Paul privately.
Larry Hendry
----- Original Message -----
From: sikorsky <vulture.squadron@...>
so here's the plan - a quad voltage source, four
pots, four jacks, very rough & ready
this is probably (yeah right) a silly question, but can
i just hook a pot directly up to the power supply and
stick a suitable 1/4W resistor either side to keep the
max levels to within -10v to +10v or is there
something i've forgotten..?
or should i keep levels to within -5 to +5v..?