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PHOBoS
Joined: Jan 14, 2010
Posts: 1003
Location: Moon Base
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 Posted: Wed Jan 02, 2013 1:31 pm Post subject:
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found some info on how to make a PUT with an NPN + PNP here (haven't tested it yet myself, since I have PUT's).
And I recorded a drone thingy which you can find here
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PHOBoS
Joined: Jan 14, 2010
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analog_backlash
Joined: Sep 04, 2012
Posts: 246
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| Posted: Wed Jan 02, 2013 4:30 pm Post subject:
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| PHOBoS wrote: | | found some info on how to make a PUT with an NPN + PNP here (haven't tested it yet myself, since I have PUT's). |
I've been on that site before, but I hadn't noticed the PUT bit. I've seen a very similar arrangement of NPN + PNP to explain thyristor action (which is also a four layer device), in my ancient copy of "A Practical Introduction to Electronic Circuits", which looks like this one:
http://www.amazon.co.uk/Practical-Introduction-Electronic-Circuits/dp/0521313120/ref=la_B001IZV9RY_1_1?ie=UTF8&qid=1357168494&sr=1-1
I got it as a school prize  , but it's only recently that I've actually started reading it (rather than blindly copying the schematics).
| PHOBoS wrote: | | And I recorded a drone thingy which you can find here |
I really like the sound of Schrödinger's Drone, especially the filtery swoops and the added background melody.
| PHOBoS wrote: | | trying some modulations with another PUT oscillator, but what i got now sounds more like a guinea pig |
Not so sure about Schrödinger's Guinea Pig, but it's early days! I will have a play with the circuit again tomorrow and see what I can get it to do.
Gary |
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PHOBoS
Joined: Jan 14, 2010
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Location: Moon Base
Audio files: 254
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| Posted: Thu Jan 03, 2013 9:42 am Post subject:
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| analog_backlash wrote: |
I really like the sound of Schrödinger's Drone, especially the filtery swoops and the added background melody. |
 , nice thing is that I didn't add a melody, it's all just added EFX, and that one is caused by a flanger.
I might add some more layers to it,. maybe some low drones and piano sounds.
| Quote: | | Not so sure about Schrödinger's Guinea Pig, but it's early days! I will have a play with the circuit again tomorrow and see what I can get it to do. |
I think it needs some more training, I did get some weird sounds out it by adjusting the pots to the point where it
almost stops oscillating. I'll see if I can record some of that. I was thinking of making a siren out of it (release of poison ?)
Also got something that sounds a bit like a geiger counter (to keep in line with the theme). ticks getting faster when
the LDR's get less light.
As for modulating the original Schrödinger II circuit, a simple 555 envelope generator comes to mind,
so you can set rise and fall times. Or maybe just using a transistor and some caps. then trigger it with some random
generator, could be teacandle LED(s) through a divider. (more then one combined to make it less predictable)
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RingMad
Joined: Jan 15, 2011
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Location: Montreal, Canada
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analog_backlash
Joined: Sep 04, 2012
Posts: 246
Location: Aldershot UK
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| Posted: Fri Jan 04, 2013 5:01 am Post subject:
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| PHOBoS wrote: | , nice thing is that I didn't add a melody, it's all just added EFX, and that one is caused by a flanger.
I might add some more layers to it,. maybe some low drones and piano sounds. |
I was wondering about that, because the sound was so subtle (especially early on) but by the end, I convinced myself that it was an added melody.
| PHOBoS wrote: | I think it needs some more training, I did get some weird sounds out it by adjusting the pots to the point where it
almost stops oscillating. I'll see if I can record some of that. I was thinking of making a siren out of it (release of poison ?)
Also got something that sounds a bit like a geiger counter (to keep in line with the theme). ticks getting faster when
the LDR's get less light.
As for modulating the original Schrödinger II circuit, a simple 555 envelope generator comes to mind,
so you can set rise and fall times. Or maybe just using a transistor and some caps. then trigger it with some random
generator, could be teacandle LED(s) through a divider. (more then one combined to make it less predictable) |
I am really going to have a look it again today (I went off at a tangent yesterday) and I'll have a look at your latest suggestions. I was also thinking about using the 1 transistor VCA from your Enneatronic Spectralizer and amplitude modulating it with a simple LFO.
| RingMad wrote: | I haven't had much time to play with this circuit nor read up on the link about PUTs. I like the timbre of this thing, but haven't figured out quite how I'd want to use it.
In the meantime, FYI, here's a scope shot of the pulses of one of the PUT oscillators, which were indeed harder to capture. I had to "zoom in" a lot... 5mV/s. and 5ms/div., and then it was a bit problematic for the camera to focus. |
You've captured the PUT pulses better than I managed to - they are tricky! On the subject of reading, I also rediscovered a document about triggering SCRs, which has a section about PUT oscillators (starting on p43):
http://legacy.littelfuse.com/data/en/Application_Notes/01_trigg.pdf
This document is probably a little OTT for this forum, but it may be useful to somebody.
Gary |
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PHOBoS
Joined: Jan 14, 2010
Posts: 1003
Location: Moon Base
Audio files: 254
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| Posted: Sun Jan 06, 2013 2:35 pm Post subject:
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here are 2 schematics, first one is the original Schrödinger II circuit with the modifications I mentioned before.
the 10K pots to adjust the sound (pulse-saw) and the extra resistor, but I used 68K instead of 100K to get the signal
a bit louder. (you can decrease it further if you want it louder, maybe add a pot). The LDR's are connected a bit different
too, so you can kinda fade between pot-control or LDR-control. I also added a pot for the filter.
the second schematic is the siren circuit, nothing really special,. but since I've drawn it I might aswell post it here. 
Don't have it breadboarded right now else I could record a short demo.
Right now I'm trying some ways to modulate the pitch. Instead of connecting the Anode with a resistor
directly to the positive supply rail I added another NPN transistor (2n3904). With the Collector connected to
the positive supply rail and the Emitter with a 100K resistor to the Anode of the PUT. This worked but the oscillator
only starts from a fairly high input voltage. So I did some more reading and noticed this:
| Quote: | | In this circuit the base of the transistor is held at 5v (with a 10v supply) by the two 1K resistors. Equal values give a 'stand-off ratio' of 0.5. Obviously this UJT is programmable so this ratio can be changed at will, say between 1K:10K and 10K:1K. |
So I replaced the 18K resistor with a 100K and the 33K resistor with a 10K and got a much wider range now.
I will do some more experimenting with that setup and post results.
| Description: |
| Original Schrödinger II schematic with PHOBoS mods |
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"My perf, it's full of holes!"
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Last edited by PHOBoS on Mon Jan 07, 2013 2:14 pm; edited 1 time in total |
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analog_backlash
Joined: Sep 04, 2012
Posts: 246
Location: Aldershot UK
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| Posted: Mon Jan 07, 2013 8:40 am Post subject:
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Hi PHOBoS,
I've just tried out your new version of the Schrödinger II and it does sound better than the original (apart from the fact that I'm sometimes getting a bit of distortion - it may just be dodgy breadboarding, as I rushed it a bit).
| PHOBoS wrote: |
Right now I'm trying some ways to modulate the pitch. Instead of connecting the Anode with a resistor
directly to the positive supply rail I added another NPN transistor (2n3904). With the Collector connected to
the positive supply rail and the Emitter with a 100K resistor to the Anode of the PUT. This worked but the oscillator
only starts from a fairly high input voltage. So I did some more reading and noticed this:
| Quote: | | In this circuit the base of the transistor is held at 5v (with a 10v supply) by the two 1K resistors. Equal values give a 'stand-off ratio' of 0.5. Obviously this UJT is programmable so this ratio can be changed at will, say between 1K:10K and 10K:1K. |
So I replaced the 18K resistor with a 100K and the 33K resistor with a 10K and got a much wider range now.
I will do some more experimenting with that setup and post results. |
Sounds like an interesting idea. I was modulating the PUT oscillators simply by passing a low frequency modulation source directly to the anodes of the PUTs. It works, but it's probably not the best way of doing it. I was using a 555 as the 'LFO' which was low-pass filtered by a resistor and a capacitor, to give charge/discharge curves rather than a rectangular wave. This was for test purposes only. It's not a good LFO, as you need to change the R and C values as you adjust the frequency!
Gary |
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PHOBoS
Joined: Jan 14, 2010
Posts: 1003
Location: Moon Base
Audio files: 254
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| Posted: Mon Jan 07, 2013 2:09 pm Post subject:
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| analog_backlash wrote: |
Sounds like an interesting idea. I was modulating the PUT oscillators simply by passing a low frequency modulation source directly to the anodes of the PUTs. It works, but it's probably not the best way of doing it. I was using a 555 as the 'LFO' which was low-pass filtered by a resistor and a capacitor, to give charge/discharge curves rather than a rectangular wave. This was for test purposes only. It's not a good LFO, as you need to change the R and C values as you adjust the frequency!
Gary |
That's pretty much the same as I'm doing except for the transistor, which has a high input impedance and low output
impedance. However the circuit itself allready isn't really low impedance, so modulating it directly (especially with a 555)
should work, except that you might get a small range like I did before I adjusted it. I also added a capacitor for a glide
effect (this is where the transistor comes in handy), just labeled C since it's value is dependent on your own
preference. Maybe a rotary switch with a couple of caps and/or a potentiometer in series is useful here.
Anyway here's the circuit for one oscillator, (I left the filter out of the schematic). you could feed a modulation
signal to the 500K pot at the point where it's connected to the LDR/Switch. (Leave those out is you do or use a diode in series)
O and I left the 10K waveshape pot out of this one since it reduces the range quite a lot.
| Description: |
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1477 Time(s) |
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http://phobos.000space.com/
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PHOBoS
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analog_backlash
Joined: Sep 04, 2012
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Location: Aldershot UK
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| Posted: Wed Jan 09, 2013 4:06 pm Post subject:
Re: The cat is still alive |
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| PHOBoS wrote: | Did some minor changes and added a 1 transistor VCA, or maybe it should be called an LCA
(resistor values depend on the used LDR and your own taste) |
I'll probably have a go at this tomorrow. Haven't been feeling too great over the last few days (some kind of bug, but thankfully, not the winter  bug) so I haven't felt up to doing much. I did try a single transistor VCA after the filter, but not much happened and feeling crap, I gave up. It usually is down to a stupid mistake I've made, when something doesn't work. Hopefully, my brain might be firing on a few more cylinders tomorrow.
Are you planning to use tea-light LEDs on all/any of the LDRs or are you using the waving hands approach?
Gary |
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Ralphperez
Joined: Jan 05, 2013
Posts: 3
Location: Virginia
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| Posted: Thu Jan 10, 2013 12:46 am Post subject:
Re: Schrödinger II: The Cats Strike Back |
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| analog_backlash wrote: | Hi,
This circuit came about while I was thinking about buzby's stripboard challenge:
http://electro-music.com/forum/topic-55837.html
I never did think of any great ideas (which would fit on 5 x 6 holes piece of stripboard), but it did start me playing with PUT oscillators, as you only need a single PUT to make one. What I did eventually produce (only on the breadboard at the moment) was the circuit below. Because the PUT oscillators produce very narrow spikes, the sound is a bit whiny and rather cat-like. To enhance the cattiness, I mixed the output of two PUT oscillators and passed the output into a twin T filter. The frequencies of all 3 parts are controlled by led lighting, so by waving your hands over it, you can get quite annoyingly accurate cat-like sounds. The two pots (actually presets on the breadboard) are only there for fine tuning and are not strictly necessary. I built it for a 12V supply, but it does work on a 9V battery.
I've put it here just out of interest, as it may (or may not) inspire someone to come up with a more musical effect.
Gary
P.S. I know it's not strictly a lunetta, but you could use CMOS oscillators in place of the PUTs, if you wanted to (but would it be as catty?). |
Hey thanks for sharing circuit. Very helpful in network analysis |
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PHOBoS
Joined: Jan 14, 2010
Posts: 1003
Location: Moon Base
Audio files: 254
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| Posted: Sun Jan 13, 2013 7:37 pm Post subject:
The cat is still alive |
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| analog_backlash wrote: |
Are you planning to use tea-light LEDs on all/any of the LDRs or are you using the waving hands approach? |
For now I think I will go for the waving hands  and probably some modulation inputs. I didn't find the teacandles
too interesting as a modulation source, probably because you can hear them very well in the signal. But I have plenty
of PUT's to play with so maybe I make a teacandle version, with a bunch of them it might get interesting.
But at the moment I'm distracted by a PWM circuit, so I'm not sure what I'll finish first 
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http://phobos.000space.com/
http://www.acidtrash.com/ |
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analog_backlash
Joined: Sep 04, 2012
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Location: Aldershot UK
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| Posted: Thu Jan 17, 2013 7:05 am Post subject:
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I've finally got round to to trying out the Schrödinger II - V circuit that you posted. I found that I had to make some minor changes, as I bought some more (cheap) LDRs and they have different characteristics to my older ones (lower resistance, basically). At the moment, I've got 2 of your circuits feeding into the LCF (if you can have an LCA, I can have an LCF). I'm also experimenting with my 555 LFO frequency modulating the 2 oscillators. I'm going to try replacing the 555 with a 4069UBE LFO, as I think this might give better results.
The problem is, that I now have 5 LDRs to "play" and on a breadboard, it's hard to modulate one without affecting the others to some extent. I might actually have to put it in a box eventually...
If I get any good results, I'll post them.
| Ralphperez wrote: | | Hey thanks for sharing circuit. Very helpful in network analysis |
Sorry for the late reply and thanks 
Gary |
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PHOBoS
Joined: Jan 14, 2010
Posts: 1003
Location: Moon Base
Audio files: 254
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| Posted: Thu Jan 17, 2013 12:07 pm Post subject:
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sure you can have your LCF
It's indeed tricky to play without effecting the others, I allready had the same problems with only 3 LDR's on a breadboard.
And yes they can respond quite different, I think the ones I have have a minimal resistance of ±2K.
As for the oscillator, I'm currently playing around with a 4046 again, and it's surprisingly easy to use, just a cap and resistor/pot
and you got a VCO (modulate the modulator ) and you get some nice bonus features too.
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