Odp: [sdiy] ic question

[Brock Russell]

Roman wrote:
>Why would anyone want to use 2 decoders and 4016s if there's
>4051 that can replace those 4 chips?

I agree. This looks like a mid to late 70's circuit designed from
parts on hand. A bunch of regular TTL, a 555 and a 3909?
Not to say there weren't a lot of great designs from this era
that still stand up today, but this isn't one of them.

>this 3909 generator can be replaced with any oscillator.

I'm not sure this is true. The 3909 is driving an 8 ohm speaker
directly and most oscillators would have some trouble with this.
Not that I would suggest using the 3909. It is obsolete, (although
readily available from many surplus dealers), noisy and sucks a
lot of power in this configuration.

>Simplest
>would be made of one schmit gate and capacitor. Resistor
>(pot)
>adjusting frequency would be connected via switching 4051.
>And you could use another scmit gate from same chip for
>tempo
>control, i.e. U1 replacement. Plus you need 1000s times less
>power to run such circuit than original.

Yes, this design is probably a better heater or low RF generator
than a tone sequencer. At least there are LS and HC parts listed
as alternatives but to suggest running the thing from a 9V battery
makes me think it would be a good idea to figure out how much it
costs to run per hour.

>Mail me if you need exact
>drawing.
>
>This only my suggestion tho...
>
>Roman

Take his suggestion...

Brock