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kxspxr
Joined: Nov 20, 2008 Posts: 35 Location: Denmark
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Ojd
Joined: Feb 22, 2008 Posts: 66 Location: Ua
Audio files: 1
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Posted: Thu May 03, 2012 3:51 pm Post subject:
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It works!
How to get bigger output voltage?
apart from adding another opamp? |
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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 Nov 24, 2014 10:55 am Post subject:
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The 68K resistor is close to 1/2 of 100K, this is limiting the output voltage swing. This resistor must be less than the 100K feedback resistor. Try increasing the 68K by adding other resistors in series, 27K might be a good place to start (68K + 27K = 95K). If it stops oscillating, then it's too large. I don't know what precision level your resistors are, but you should know that just because are resistor says "100K" doesn't mean it's exactly 100K, it could be a little more or a little less. Another way to maximize the output swing would be to put a pot (say, 50K) in series with the 68K (wiper and one side). Then increase it until it stops oscillating then back if off until it starts to oscillate again. Remove the pot and measure with an ohm meter. Then find a suitable fixed resistor to put in place of the pot. Make sure that the fixed resistor is less than or exactly equal to the pot value. You should verify this using the ohm meter. _________________ 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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Baloo
Joined: Jul 09, 2013 Posts: 16 Location: France
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Posted: Wed Feb 04, 2015 3:34 pm Post subject:
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Would work for 12v instead 9v? |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Thu Feb 05, 2015 4:39 am Post subject:
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Power supply voltage should not matter as long as it is less than the maximum specification in the datasheet for the opamp. _________________ 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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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Thu Feb 05, 2015 6:39 am Post subject:
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How big is the output? (vpp)
I could imagine tons of these in my Eurorack... |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Thu Feb 05, 2015 7:21 am Post subject:
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The PSU voltage is 1.3333 times larger, so a good estimate would be 1.3333 times the output swing of the 9 volt version.
Best way to know is make one on a breadboard and measure it. _________________ 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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Ayab
Joined: Oct 27, 2015 Posts: 180 Location: London, UK
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Posted: Mon Dec 07, 2015 8:25 am Post subject:
Subject description: Dual-wave LFO Vero layout |
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(Again resurrecting a thread - but I think that is a good thing really )
Thanks Jovian Pyx for referring this great layout and for all the information.
I am just wondering why there is no connection for -V
Do I just wire up +V and ground with no -V?
A couple of these will be so useful
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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 Dec 07, 2015 8:34 am Post subject:
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Yes, referring to the schematic, I see a single rail (+9v) and ground. However, he creates an "internal" virtual ground that he calls "Vb", so the opamp can work properly. So this circuit needs only one positive rail and no negative rail. _________________ 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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Ayab
Joined: Oct 27, 2015 Posts: 180 Location: London, UK
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Posted: Mon Dec 07, 2015 8:44 am Post subject:
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Hi JovianPyx
Thanks for the reply - I think I should try to find the schematic for this - is it at experimentalist anon? Have started to understand schematics (as long as they are not too complicated) which I find really exciting.
Thanks again for your explanation of the range am looking at building a dual version of this and will try the measuring advice you gave.
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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 Dec 07, 2015 8:52 am Post subject:
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Isn't the schematic the link in the opening post? _________________ 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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Ayab
Joined: Oct 27, 2015 Posts: 180 Location: London, UK
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Posted: Mon Dec 07, 2015 4:40 pm Post subject:
Sockets for component flexibility |
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Yes it is thank you Jovianpyx!
On the advice of someone on Muff's I broke up some single row header and soldered the 'sockets' where the resistor legs go. The idea is to be able to experiment with the resistor values - great idea but how to get the resistors not to fall out?
Not sure the connection is reliable either.
What didn't I get Last edited by Ayab on Mon Dec 07, 2015 5:10 pm; edited 1 time in total |
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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 Dec 07, 2015 5:00 pm Post subject:
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Heh - I "see" what you're doing - it sounds like the resistor wires are very thin like for most 1/8 watt, so they aren't thick enough to make a proper "force fit". You can use resistors with thicker wires. Or you can solder a small piece of thicker wire to each end. Test the wire first, if it fits and doesn't fall out - that's a good size.
My Opinion --> When I do DIY electronics, I start things on a breadboard so I can mess around with things like resistor and cap values. Once I get it working the way I want/like, I either use that as a pattern to make one with stripboard (because it's easy to find stripboard that's laid out like breadboard), or I transfer the parts one at a time from breadboard to stripboard. Breadboards have spring contacts, so a good variety of wire sizes will connect, so you can use parts with almost whatever size wires. Breadboards also allow you to basically circuit bend any way you want. You can start out with one or more basic circuits and connect them however you want. You can probably find most of what you need schematic-wise and even layouts and PCB art right here on electro-music.com _________________ 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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Ayab
Joined: Oct 27, 2015 Posts: 180 Location: London, UK
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Posted: Mon Dec 07, 2015 5:18 pm Post subject:
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Smart idea will try soldering stronger wire on. Also my stripboard is a bit crappy and it is pushing out the track.
I agree with you that I should bread board first but have been learning this game from buying a couple of kits and then bare pcb's from here on Electro-Music.com ( ). Thought I would try and tackle some stripboard projects to help add functionality to my system.
You must be right that some general electronics knowledge (breadboarding) is a good idea.
I have been hoping this is more a jigsaw puzzle than anything else - maybe that is a bit ambitious!
Hope things are good with you and thanks for the assistance. |
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Ayab
Joined: Oct 27, 2015 Posts: 180 Location: London, UK
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Posted: Mon Dec 07, 2015 5:46 pm Post subject:
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Been trying the socketing but is a bit fiddly. Maybe putting a variable resistor makes more sense. So if I put a small variable resistor (20k) in series with the 68k that should adjust the range? |
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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 Dec 07, 2015 6:27 pm Post subject:
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Yes, that would adjust the amplitude of the output. _________________ 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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Ayab
Joined: Oct 27, 2015 Posts: 180 Location: London, UK
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