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MusicMan11712
Joined: Aug 08, 2009 Posts: 1082 Location: Out scouting . . .
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Posted: Sat Nov 06, 2010 6:23 pm Post subject:
555 timer circuit |
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While looking through a box of old files on music, I found my 555 timer circuit from a few decades ago. The actual object can be seen here (well, most of it): http://electro-music.com/forum/post-278450.html&highlight=#278450
So, here's the diagram. I may try to rebuild it to see if it still works as I know some of the wires fell off over the years. |
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MusicMan11712
Joined: Aug 08, 2009 Posts: 1082 Location: Out scouting . . .
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Posted: Fri Jan 07, 2011 5:43 pm Post subject:
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I just found another sketch of my ancient 555 timer sound device showing ideas I had for modifying it. |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Sun Jan 09, 2011 12:43 pm Post subject:
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When do we get to hear what it does? _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24075 Location: The Netherlands, Enschede
Audio files: 277
G2 patch files: 320
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Posted: Sun Jan 09, 2011 12:49 pm Post subject:
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JovianPyx wrote: | When do we get to hear what it does? |
Seems to be on *now* on PHOBoS' port _________________ Jan
also .. could someone please turn down the thermostat a bit.
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Sun Jan 09, 2011 1:06 pm Post subject:
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hmm. I was a tad late... He's offline... _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24075 Location: The Netherlands, Enschede
Audio files: 277
G2 patch files: 320
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Posted: Sun Jan 09, 2011 1:13 pm Post subject:
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It'll come back I guess _________________ Jan
also .. could someone please turn down the thermostat a bit.
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
Audio files: 705
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
Audio files: 705
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Mon Jan 10, 2011 7:47 am Post subject:
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I noticed that too - about the pin 3 to pin 3 connection... Also, it's not clear to me where power + is connected. Is it on the upper "bus" that connects the pins 8?
I've seen circuits like this before, where outputs are connected together to get a kind of ring modulator sound. But as you point out, with pin 3 of one connected to pin 3 of the other, it's possible for + to connect to - through the output transistors. Some circuits like this have recommendations to use batteries that are partially drained so as not to provide enough current to allow damage to the ICs. A dubious recommendation at best I think. Low voltage can help too. Or one could simply put a resistor between the + rail and pin 8 of each chip to force limiting the current to some acceptable level. This would prevent chip self destruct and/or overheating.
I see that in your second schmatic (PHOBoS) you have eliminated the right 555 pin 3 connection to the other pin 3 - yet in both of Steve's drawings, they are connected together or can be through the switches. This connection would also appear to provide self modulation of the right 555 timer.
It might be interesting to use a high input impedance opamp to get a signal from the timing capacitor(s). _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
Last edited by JovianPyx on Mon Jan 10, 2011 8:28 am; edited 1 time in total |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
Audio files: 705
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Posted: Mon Jan 10, 2011 8:27 am Post subject:
Testing Dr. Steve's 555 Circuit |
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JovianPyx wrote: | I noticed that too - about the pin 3 to pin 3 connection... Also, it's not clear to me where power + is connected. Is it on the upper "bus" that connects the pins 8? |
yes, power + is connected to the topline in the schematic (which is connected to pin 8 )
Quote: | I see that in your second schmatic (PHOBoS) you have eliminated the right 555 pin 3 connection to the other pin 3 - yet in both of Steve's drawings, they are connected together. This connection would also appear to provide self mutilation of the right 555 timer. |
Since the second 555 got hot and it just doesn't make sense to me, I
removed that connection, It didn't really produce any usefull noise in this
configuration .
Quote: | It might be interesting to use a high input impedance opamp to get a signal from the timing capacitor(s). |
yes, that will give a nice sawtooth/triangle , I've actually used that with
transistors instead of opamps for fading LED's and producing sounds.
--------------------------------------------------------------------------------------
continuing from my previous post
I got some sound of it but only after removing the 220uF Cap,. (maybe
this is because I use BC547 of transistors)
So with the same components I came up with something that does
what I think the original circuit is intended to do. When the switch is closed
the 220uF cap is quickly charged which then (through the transitors) turns
the sound on. when the switch is opened the cap slowly discharges and
the sound slowly fades out again.
I changed the 4.7uF cap to 1uF since I like the sounds it produces at
higher LFO frequencies. I reduced the 220uF cap to 22uf for shorter
decays and I also made a slight change to get a line signal so I can
connect it to an amp.
posted below is the schematic and some sound samples.
(I'm currently using LDR's in series with the frequency pots and let the
setting sun control it. Excerpts will probably be uploaded later)
Description: |
Dr. Steve's 555 Ciruit Heavily modified by PHOBoS |
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Filesize: |
10.83 KB |
Viewed: |
656 Time(s) |
This image has been reduced to fit the page. Click on it to enlarge. |
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With the switch closed and starting with all pots turned down, then while sweeping the frequency pot of the second 555 timer: - increasing the Pulse Width pot in steps - increasing the Frequency pot of the first timer in steps - increasing both pots (fun) |
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Dr Steve's 555 Circuit - Demo 1 (Jan 10, 2011).mp3 |
Filesize: |
4.97 MB |
Downloaded: |
1457 Time(s) |
Description: |
Triggered by my Treequencer and with a small (110ms) delay turning all pots. |
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Dr Steve's 555 Circuit - Demo 2 (Jan 10, 2011).mp3 |
Filesize: |
5.37 MB |
Downloaded: |
1333 Time(s) |
_________________ "My perf, it's full of holes!"
http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube Last edited by PHOBoS on Sat Jan 15, 2011 9:21 am; edited 1 time in total |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
Audio files: 705
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
Audio files: 705
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
Audio files: 705
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Posted: Sat Jan 15, 2011 9:54 am Post subject:
Testing Dr. Steve's 555 Circuit Subject description: CV control |
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Next test: CV control.
Using a vactrol (LDR-LED combo) in series with the second 555 frequency
pot I was able to use a sequencer to change the frequencies.
I also made some further adjustments to the circuit.
- A couple of different caps to choose a different decay time.
(this was also suggested in Dr. Steve's second schematic).
- An extra cap to choose a higher frequency for the first 555.
- Resistors in series with the frequency pots so I can use the full range.
- A LED and an extra resistor to get rid of the soft noise when the circuit is
not being triggered. (This LED also functions as a very nice indicator)
- A simple trigger circuit connected parallel to the Trigger switch.
(before I just hooked up the Treequencer instead of the switch)
Posted below is the schematic and a recording done by using a sequencer
for both CV control and triggering the circuit. (and delay for the nice phasing)
If you listen closely you might notice that the circuit produces some weird
background noises too.
Description: |
Dr. Steve's 555 Ciruit Heavily modified by PHOBoS (rev3) |
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Filesize: |
17.89 KB |
Viewed: |
490 Time(s) |
This image has been reduced to fit the page. Click on it to enlarge. |
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Description: |
Using a sequencer controlled Vactrol to change the frequency of the second 555. Circuit is triggered by the CLK of the sequencer |
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Download |
Filename: |
Dr Steve's 555 Circuit - Pulsing Vactrol Drone (Jan 13, 2011).mp3 |
Filesize: |
5.94 MB |
Downloaded: |
1213 Time(s) |
_________________ "My perf, it's full of holes!"
http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Sat Jan 15, 2011 10:00 am Post subject:
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The LED looks like it's drawn backwards... _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
Audio files: 705
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Sat Jan 15, 2011 10:31 am Post subject:
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I figgered that would be the answer, but I had to make sure... very odd... That means the LED conducts only when pin 3 of the right 555 is at ground potential, so the + end of the circuit is somewhere else. I see two candidates, the trigger switch through the 2.2k through the base-collector diode (which might not be a good thing for the transisitor)
OR
possibly from + to the collector of left transistor through it's collector-base diode and then avalanching the emitter base junction of the right transistor (????)... Very odd indeed. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
Audio files: 705
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Posted: Sat Jan 15, 2011 11:41 am Post subject:
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JovianPyx wrote: | ..,the trigger switch through the 2.2k through the base-collector diode (which might not be a good thing for the transisitor |
I think this could be the right answer. I just took out the left transistor and
100K resistor (so the Emitter of the first transistor is floating) and the LED
responds the same. Don't know if the transistor likes it,. but it works (for now ) _________________ "My perf, it's full of holes!"
http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Sat Jan 15, 2011 11:50 am Post subject:
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The caps on the multi-switch might also be able to supply the + side of the circuit while they are charged. I'd bet the LED might change brightness when the cap value is changed.
Wonderful mental gymnastics, eh? _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
Audio files: 705
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Posted: Sat Jan 15, 2011 1:09 pm Post subject:
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JovianPyx wrote: | The caps on the multi-switch might also be able to supply the + side of the circuit while they are charged. I'd bet the LED might change brightness when the cap value is changed. |
well the LED reacts as follows: it flashes with the frequency of the first 555
between bright and dim and fades as the cap discharges (and the sound dies
out). Funny thing if I short the LED the sound barely changes (just doesn't die
out completely) _________________ "My perf, it's full of holes!"
http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
Audio files: 705
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MusicMan11712
Joined: Aug 08, 2009 Posts: 1082 Location: Out scouting . . .
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Posted: Mon Jan 17, 2011 7:05 am Post subject:
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Thank you so much for breathing new life into my ancient experimental 555 circuit, PHOBos. Thanks also to JovianPyx for adding to the discussion of the design and redesign, and to TJookum for participating in the demos.
Now that I found four more of my ancient 555s and a whole bunch of other parts (including the transistors taken from an old Magnavox Odyssey*), perhaps I can build your version--or something close to it--without taking my museum piece apart!
Steve
*http://www.magnavox-odyssey.com/Manuals.htm has a couple of versions of the service manual as well as operating manuals.
Footnote:
I used a 9 volt battery which was probably not operating at full capacity most of the time. |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5581 Location: Moon Base
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-minus-
Joined: Oct 26, 2008 Posts: 787
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MusicMan11712
Joined: Aug 08, 2009 Posts: 1082 Location: Out scouting . . .
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Posted: Tue Jan 18, 2011 6:29 pm Post subject:
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LOL!!!!!!
I remember those little boards. They were fun to desolder!!!!
Either I found it in the trash or someone gave it to me as a non-working unit. I am guessing this was about 30 years ago or so. Back then, it was worthless.
Lemme see what other trash--errrr, I mean collector's items I have around here. I wonder what they are worth. Hmmmmmm. A Roland MT-32? A Casio CZ-3000? A Commodore 64? About 20 or so SCSI Cables?
Steve |
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-minus-
Joined: Oct 26, 2008 Posts: 787
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Posted: Wed Jan 19, 2011 11:02 am Post subject:
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I was going to comment but it turned into a rant and I hit the delete button! Anyway, I'll forgive you for your transistor barbarianism. You were not to know... Besides, I sent a Jupiter 4 to the garbage dump in 1992 because the on/off button was broken |
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