[sdiy] 555-based ADSR that refuses to work with 9v

[Scott Gravenhorst]

music.maker at gte.net wrote:
>If the large resistors are a problem, the CMOS version (7555) might help. 
>The datasheet I have says "Extremely low input currents of 20pA".  It also
>claims a PS voltage of 18V (abs. max.).  However, since these are series
>pots, just reducing their value by turning them "down" should cause the
>circuit to work at some point - if that's what the problem is.  I can't see
>anything about the circuit that would prevent it from working at 9 volts and
>I don't see a reason that you even need a negative supply at all (You mention
>a +/- 9V supply, are you connecting the -9V as the circuit's ground?  That
>could be a problem).  I'd bet the circuit should work from a single +5V >supply.

Well, except for the opamp part, that needs a dual supply, but still, pin 1 of
the 555 should be connected to zero volts (ground) and not -V.  I don't know
that you're doing that, but just in case...  It really sounds like something is
miswired.  In this schematic, watch the crossovers versus dots where dots mean
to connect and no dot means jump over.

>
>
>=?us-ascii?Q?Jaroslav_Lukes?= <lsh.synth at seznam.cz> wrote:
>>> From: Karl Ekdahl [mailto:elektrodwarf at yahoo.se]
>>> Hi Jaroslav, i've tried changing the 4.7k to Reset
>>> since it seems the VCC feed was to low, but without
>>
>>Not that,I was think about resistors with Mohm values (A/D/S/R).
>>
>>> any luck. The 555's i tried are CA555CE from Harris
>>> and RCA, and also a NE555N from ST. Earlier i also
>>> tried NE556A from ST. I can't verify wheter this
>>> circuit does actually run from a +-15 since i don't
>>> have anything but a +-9V supply here (i've moved
>>> recently).
>>
>>Hmmm. I think that you use all versions that are less or more different from
>>original. Use 555 from philips or TI. In my country before many years was
>>published list of differences between mfgr's for 555, but I could not find
>>it now. I was remember Philips and TI only that are good.
>>
>>Regards, JL.
>>
>
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>-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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---------------------------------------------------------
- Where merit is not rewarded, excellence fades.
- Hydrogen is pointless without solar.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- The only good terrorist is a dead terrorist.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- Autodidactic Master of Arcane and Hidden Knowledge.