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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Sat Feb 20, 2016 3:32 pm Post subject:
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I apologize as well, I didn't mean to sound prickly. Just suggesting that the opportunity to look at others' work is usually a good learning experience in this hobby. |
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Grumble
Joined: Nov 23, 2015 Posts: 1294 Location: Netherlands
Audio files: 30
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Posted: Sat Feb 20, 2016 3:56 pm Post subject:
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I totally agree!
The first thing I did when the decision was made that I was going to build a synth was reading about synthesizers and watching youtube flicks (I have watched literally hundreds of youtube uploads, from simple diy projects to demo's of unreachable modular synths as the moog system 55)
Just to get an idea what I want my future synth to have. Get some knowledge about modulation, control voltages, oscillators (or generators in my case), filters, do's and dont's in synthesizers.
That was not the wheel I want to invent, the real fun for me starts when I buy a perfboard and get components and start building.
Exactly the reason why I never get past prototyping |
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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 Feb 20, 2016 4:34 pm Post subject:
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heh - no kidding, I have countless times recorded music through circuits on a solderless breadboard. Sometimes those things made it to stripboard, sometimes not. Never anything etched. _________________ 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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Smada
Joined: Feb 18, 2016 Posts: 5 Location: Smada
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Posted: Mon Feb 22, 2016 2:15 pm Post subject:
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Hi guys, can anyone clarify what pin 1 is for. I currently have nothing going into it and the circuit is not working correctly. |
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Grumble
Joined: Nov 23, 2015 Posts: 1294 Location: Netherlands
Audio files: 30
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Posted: Mon Feb 22, 2016 2:47 pm Post subject:
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before someone can answer this you first have to tell us which diagram you are referring to... |
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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 Feb 22, 2016 3:16 pm Post subject:
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Smada wrote: | Hi guys, can anyone clarify what pin 1 is for. I currently have nothing going into it and the circuit is not working correctly. |
I'm assuming you're referring to pin 1 of the CD4046 IC.
The best description of what this pin does is in the datasheet - it's a good idea to read through it (more than once). I've not used pin 1 for audio work, but it essentially outputs some tiny pulses of phase difference between the VCO and input signal while locked as the IC tracks the input.
It's worth noting that for this IC, Texas Instruments has a very different and more detailed datasheet than other mfrs. Some very interesting reading material in it regarding the clever VCO they used.
My advice with this IC is to start with a straight "follow the signal" circuit before moving on the frequency multiplication. Definitely an opportunity to use a solderless breadboard for fun and education. _________________ 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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Grumble
Joined: Nov 23, 2015 Posts: 1294 Location: Netherlands
Audio files: 30
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Posted: Mon Feb 22, 2016 11:47 pm Post subject:
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Could be, but the picture of the third post in this tread also has a pin 1 for input... |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Tue Feb 23, 2016 6:04 am Post subject:
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I see. That's some sort of frequency doubler. I haven't studied it to know how it works, but the pin 1 on that circuit (3rd post) is a signal input. Put the signal you want to freq double on that pin 1. Best way to know how it works and what it does is to breadboard it and try 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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Grumble
Joined: Nov 23, 2015 Posts: 1294 Location: Netherlands
Audio files: 30
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Posted: Tue Feb 23, 2016 6:55 am Post subject:
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Cynosure wrote: |
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When looking at the RC combination of C1 R1 and C2 R2 the pulses at E and F calculate to about 2 usec! That might be to short.
Considering that 20kHz will be the max frequency out of the doubler, to be on the safe side a pulse of 50 usec should be the minimum pulsewidth.
That calculates to about a capacitor of 560pF.
(for this I assumed that the output impedance of N2 = 0 ohm and the input impedance of N3 and N4 are infinite and the schmitt trigger trips at around 1/2 Vcc).
Check for yourself |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
Audio files: 705
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Grumble
Joined: Nov 23, 2015 Posts: 1294 Location: Netherlands
Audio files: 30
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Posted: Tue Feb 23, 2016 8:47 am Post subject:
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L´Andratté
Joined: Sep 23, 2012 Posts: 150 Location: Hamburg, Germany
Audio files: 5
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Posted: Tue Mar 01, 2016 12:32 pm Post subject:
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There´s the slacktave design on diystompboxes, that I have built, which uses the same snippet for frequency doubling and it works very good! |
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Smada
Joined: Feb 18, 2016 Posts: 5 Location: Smada
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Posted: Tue Mar 01, 2016 4:42 pm Post subject:
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HEy sorry for the slow reply, yes it was the pin 1 on the 4046. I feel I have a decent grasp on how the PLL works and have been making my way through the datasheet/other resources. I have tested the VCO section on its own and it works as expected, likewise the divide by 2 flip flop. But when i connect the whole circuit up its not working, changing the input frequency has no impact on the output frequency (which just stays the same). However, I have just examined the circuit and saw it wants 3nF between pins 6 and 7 - I have been putting 300nF between them!!!!!! I also ignored the 1Meg and 10Meg variable resistors on pins 11 and 12 but I assume they make a big difference to the VCO oscillation frequency and thereby the circuit as a whole. I didn't have any variable resistors to hand so I just ignored them which is probably not the best idea. |
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Smada
Joined: Feb 18, 2016 Posts: 5 Location: Smada
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Posted: Wed Mar 02, 2016 11:42 am Post subject:
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Hey so I was messing around with it more today and set it up with 3nF between pins 6 and 7. with an 1Meg resistor on pin 11 and 10Meg on pin 12 (I don't have any variable resistors to hand). The frequency doubler worked to a satisfactory accuracy but only on a certain frequency range. It double an input frequency from about 900hz to 1200hz (outputting 1800-2400hz) and for all frequencies outside the range it just outputted 1900hz. I'm guessing this is because of the VCO capacitor and resistor setup? Or was your design only supposed to work over a specific frequency range JovianPyx? |
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