the chaos i mentioned: Oscila-fold-o-matic (using PUT and Thyristor for clippin)

[iainpunk]

i have experimented with a saw-tooth generator where the generator ......  ill draw up a rough approximation in falstad, to be posted later today.

total chaos will ensue

cheers, Iain

I'm interested in this chaos you mention. perhaps start a new thread?

sure, this is what i was thinking about, it only oscillates above a certain threshold, and the frequency is dependent on the input amplitude.

its based on a wave folder (all pass filter) so the amplitude of the oscillations can be matched to the amplitude of the output signal instead of stopping in the middle.

the feedback and clipping diodes are 4148, the diodes near the oscillators are LED's



this is only a proof of concept, and its running on +/-5v bipolar supply, and some reworking to 9v single is needed.
the Vb should be buffered since there is quite a lot of ground current in this circuit.

if anyone is interested and wants to breadboard it, ill be glad to rework the schematic for 9v, add a booster and stuff to make it work for guitar, since all my breadboards are already occupied with school and fuzz projects. (in hindsight, i should have asked for breadboards for Sinterklaas [saint Nicholas day, aka Dutch Christmas])

cheers, Iain

[duck_arse]

it's times like this I wish I'd snapped up those bargain ujt's I saw recently.

[edit :] 2N6028 - 10 for 5$, still available. blast!

[iainpunk]

i don't know if the schematic works with UJT's, but PUT's and Thyristors (they are each others complementary like p and n channel or pnp and npn) can easily be made from 2 BJT's like the schematic shows. its also not very often i feel the need to do something with an UJT, when it can be done with the cheaper bjt sets.

i do have a few old ones in a box somewhere. makes me wonder if there are mojo germanium UJT's, switching needs that germanium warmth... haha (reminds me of a 4chan thread analog discussing video synthesis and some idiot constantly derailing our civilized conversation with insisting we should use tubes for their ''warmth'' while having no idea how video synthesis works... by the way, tubes can't do Pythagoras, BJT's can)

cheers, Iain

[11-90-an]

if anyone is interested and wants to breadboard it, ill be glad to rework the schematic for 9v, add a booster and stuff to make it work for guitar, since all my breadboards are already occupied with school and fuzz projects. (in hindsight, i should have asked for breadboards for Sinterklaas [saint Nicholas day, aka Dutch Christmas])

cheers, Iain

Me me I'm interested... 

For Christmas I got some more parts, some switches, breadboards and a drill (without drillbits... )

[iainpunk]

allright, ill start drawing then, im quite curious about the sounds it creates.
i want 2 or 4 opamps, i currently have 3 in the design, any added ideas?

cheers, Iain

[iainpunk]

EDIT: mistake, there should be a 1k resistor in series with the variable resistance between the first opamp and the transistor oscillators, if not, it will allow huge currents to be drawn from that 1st opamp



i found a use for the extra opamp, make up gain for Ge or other low Vf clipping



you should double check the schematic, but in 95% sure this would / should work.

if you think the oscillations are to much, just leave out one of the transistor sets, that will lessen the craziness a bit, i guess.

cheers, Iain

edit:
i didn't implement much tone shaping/filtering since i want the chaotic ''wave shaping'' and oscillators to determine the tone, not the filters, but feel free to experiment with values to change the tone

[11-90-an]

Soo.. first observation... 1st opamp needs a capacitor from the 2.2k resistor to Vb otherwise it won't do any amplification and no sound...

more observations to come 

EDIT:

Built the full thing (except the last opamp stage due to lack of breadboard space, extra BBs didn't arrive yet..., and my diodes with lowest vf were 1n4148s... ) and it seems best to leave the gain pot on max, so just a fixed resistor would be fine. I used a 1M resistor for more smoothness...(lesser gain=Less smooth) It also seems the diodes in the feedback loop of the 2nd-to-last opamp heavily change the sound/tone. Use 1n4148s for a more nasal /trebly tone and LEDs for a fuller/more bass(in comparison with 1n4148s) sound. If anyone will build this I recommend socketing those diodes.

Really chaotic...

[duck_arse]

come on, 11-90-an, we want sounds!

nice work, both parties.

[iainpunk]

come on, 11-90-an, we want sounds!

nice work, both parties.

yes, i'm extremely curious about the sounds.
also, thanks to Vivek and whoever designed the UglyFace for the inspiration.

cheers

[duck_arse]

from what I read today, Jameson Rowe Fundamenals of Solid State, the PNPN thyristor or Shockley Diode is made with/like "very low gain internal transistors". and, with the top P as Anode and the bottom N as Kathode, you can use the upper PN junction as a Programmable Unijunction gate [AG], and/or the lower PN junction as an SCR gate [KG].

I hope some of this is correct.

[garcho]

"...whoever designed the Ugly Face...

Hwhat?! You don't know who Tim Escobedo is? Major influence around here, especially for those who like to tinker more than clone. Many diy projects took off from his "circuit snippets".

[garcho]

http://www.jiggawoo.eclipse.co.uk/guitarhq/Circuitsnippets/snippets.html

[iainpunk]

from what I read today, Jameson Rowe Fundamenals of Solid State, the PNPN thyristor or Shockley Diode is made with/like "very low gain internal transistors". and, with the top P as Anode and the bottom N as Kathode, you can use the upper PN junction as a Programmable Unijunction gate [AG], and/or the lower PN junction as an SCR gate [KG].

I hope some of this is correct.

this is fully correct.

"...whoever designed the Ugly Face...

Hwhat?! You don't know who Tim Escobedo is? Major influence around here, especially for those who like to tinker more than clone. Many diy projects took off from his "circuit snippets".

i know who Tim Escobedo is, but i didn't remembered he designed the ugly face. oops i guess.
the last time a took a look at that schematic was quite a long while ago, i remember the basic functions and order of operation, i forgot who designed it... how do i repent for forgetting Saint Escobedo's works?

cheers, Iain

[garcho]

how do i repent for forgetting Saint Escobedo's works?

Pick a "circuit snippet" at random and take it way too far!

[iainpunk]

how do i repent for forgetting Saint Escobedo's works?

Pick a “circuit snippet” at random and take it way too far!

i will do that!

i want to maybe modify the he*k out of the Harmonic Jerculator with one of the wah- type circuits and an octave up on top.

cheers, Iain