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Cheap PIC based ADSR


Tanstaafl

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I mentioned this on the chat room the other day, but interest was low...... this is a GREAT ADSR!

check it out... parts only cost about 3 bux (USD)... well the pots are not cheap but the circuit board only uses about 10 resistors, 3 or 4 caps, a 16f684 pic (14 pin) and an op amp.

I have built 3 of these so far and am very happy with the performance.

here's the link: http://www.tomwiltshire.co.uk/sdiy/envgen.html

he's also got a really nice LFO based on the same circuit.

happy midiboxing!

gb

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That is great. Maybe not for all analog lovers but doesn`t matter.

;D It was very funny to read the news from the creator`s website...

My brother has taken the plunge and got some pigs, so we've got some livestock on the farm again. The pigs are great, curious and fun. They are so obviously happy snuffling in the earth and running around in their enclosure. Much more interesting than boring old fluffy sheep, like we used to have...
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Not really sure what it is HE does for a living, I emailed him to thank him for his design, asked a couple of questions about updates.... here follows the correspondence... hope he does not mind:

Gene,

Thanks for the email, and I'm glad you like the VCADSR. I'm sure you'll like the VCLFO too. It was my favourite out of the two, mainly because of the lovely rhythmic effects you can get by setting the S&H and LFO rates so they are close but not the same. Beating between the two produces a modulation that fades in and out at the difference frequency - it's great!

I have been working on more projects, but nothing as simple or neat as the first two. I've started using dsPIC 16-bit chips, since I felt I needed the power for a good quality digital oscillator, and since doing some experiments with that, I've also started working on a digital modulation matrix, rather like the Oberheim Matrix synths. When these will see the light of day is anyone's guess, but I'll put something up when they're done!

Good luck with your projects.

Regards,

Tom

On 13 Dec 2007, at 21:34, Gene Beth wrote:

Howdy Tom !

Just wanted to drop you a line and a THANK YOU for your VCADSR design.  I have been looking for (and building envelope generators) for years and yours is the BEST!!!

I need an LFO also and yours looks like a candidate for fabrication.

If there are ever any updates, please keep me informed!!

Gene Beth

Houston, TX. USA

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Sorry for the silly question but can these two units have a regular audio source/midi synth sent into them to be modfied then outputed to a mixer? I havent gotten into analog cv stuff at the moment.

these are both sources for control voltages. To have an effect on audio, you e.g. need to apply the adsr cv output to a VCA (voltage controlled amplifier), then you get a volume envelope :)

I like the idea of digitally generated ADSRs and LFOs - as long as the output is accurate, this is actually better than analog CV sources. You get much more possibilities to configure/influence CVs in the digital domain. The actual "analogue sound" comes from the VCO/VCA/VCFs, not so much from the CV sources.

S

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Some rather random testing results:

* Board size would be about 1.5x1.3 inches. That's pretty damn small.

* Costs of components: about 4 Euros. That's pretty cheap.

Does this thing actually work (well)? ;-)

PCB already. Great! :) Thank you Nils. It would be nice to publish the brd and send the copy to the creator so he can include it to the other files.

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Second opinions and a cross-check with the original schem would be appreciated ;-)

Parts list (pin headers and board not included):

X1			20 Mhz
C1 10 nF
C2 47 nF
C3 15 nF
C4 2n2
C5 22 pF
C6 22 pF
C7 100 nF
R1 15 kOhm
R2 15 kOhm
R3 15 kOhm
R4 15 kOhm
R5 150 Ohm
OPAMP TL 072
[/code]

test_env_2_thumb.png

test_env_schem_thumb.png

1889_test_env_2_png55d96c408acf4b6139079

1891_test_env_schem_png817c55f59c9cc8bd3

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  • 8 months later...

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