questions from a newbie

[patchell]

matti at devo.com wrote:

> ok, I'm hoping someone(s) can help me with these....
>
> 1)Fatman :
> I've recently soldered together the Fatman kit. Naturally, something went wrong,
> and I'm now in the process of figuring out how to get the sucker working. The
> symptoms : the gate LED doesn't lite when I send in a MIDI note (the MIDI LED
> does, however), and there is no output, beyond what sounds like two out of synch
> saw waves playing some middle-end note (very faint, and audible only when I
> crank the output all the way up). I've done quite a bit of probing, and both
> oscillators are working fine, and I'm getting the output from the VCF pots that
> I should be (lug two of R56, the 1/2 mixer gives me nothing though). Any
> thoughts, anyone?
>
> 2) concerning different op-amps...: is there any difference between different
> op-amps, other than gain? If this is so, then it seems to me that any op-amp can
> be used anywhere, certain ones are simply more efficient.
>

    If you mean different type? (ie what is the difference between a 741, LF356,
TL071, etc), yes there is a big difference between them.  Knowing which one to
choose for a particular job will only come with expreience.  Important parameters to
consider include :
    Input Bias Current (this is the current that flows into or out of the input
terminals)
    Input Offset Voltage
    Slew Rate
    Unity Gain Crossover Frequency
    Distortion
    Input Voltage Noise
    and many many others.  But those are probably the ones you generally need to
consider the most.

>
> 3)just what does an LDR do?
>
> Many thanks....
>
> 6669the RaabidMuttn Speaks6999

--Jim
-----------------------------------------------------------------
Visit:http://www.silcom.com/~patchell/
-----------------------------------------------------------------