[sdiy] EG

[Scott Gravenhorst]

I'm a FatMan guy, but this is not the EG used in a FatMan.  But I'll take a
stab at it.  My $0.02:

When the 555 timer is at rest, i.e., before it is triggered, it's pin 3
output will be zero volts.  It will not switch to high until the timing
threshhold is reached.  This means that the 555 pin 3 is holding the control
(4016 pin 13) for the attack charge current in the off state.  So it's like
the attack pot which should supply charge current to the integration
capacitor is not switched in until the attack is already finished.  IMHO,
there is a design problem here.  Or maybe I haven't had enough coffee...




=?iso-8859-1?Q?=22R=F6nnberg=2C_Niklas=22?= <nikro at itn.liu.se> wrote:
>Hello!
>
>Some days ago I dragged out my old project, the Littleman. It's based on
>the Paia Fatman VCO and some Tom G circuits. I got some problems with the
>EG. The Release is working quite ok, and the Sustain to. But I have some
>serious problem with the Attack. The Attack is working nice for a few
>seconds after you have turned on the power, but then it doesn't work at
>all. No changes on the Attack knob makes any changes in the envelope. So
>when you turn on the synth you can have a short and nice attack time or a
>slow, but after a few seconds you can't control the attack at all. But then
>you can make slower attack times using the Decay knob, but I don't want it
>this way...
>
>Can anyone help me out?
>
>You can find the schematic here:
>http://www.itn.liu.se/~nikro/diy/littleman/littleman.pdf
>
>Thanks!
>
>/Niklas
>

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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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