Author |
Message |
Yipdeceiver
Joined: Apr 07, 2014 Posts: 4 Location: Athens GA
|
Posted: Mon Apr 07, 2014 3:47 pm Post subject:
|
|
|
A friend and I built this and it's pretty rad. One thing though, patching it through the ext signal in on the ms10 and the extra oscillator doesn't respond to the lfo. Is there anyway to make that happen? Might be more of an ms10 question I guess, but I figured you guys might have some ideas. |
|
Back to top
|
|
|
bod
Joined: Apr 28, 2009 Posts: 148 Location: Glasgow
|
Posted: Tue Apr 08, 2014 4:28 am Post subject:
|
|
|
you would need to take a signal from the ms10 lfo output and connect it to the cv input of the oscilator for that to work, but it would work. |
|
Back to top
|
|
|
Yipdeceiver
Joined: Apr 07, 2014 Posts: 4 Location: Athens GA
|
|
Back to top
|
|
|
Yipdeceiver
Joined: Apr 07, 2014 Posts: 4 Location: Athens GA
|
Posted: Thu Apr 24, 2014 2:57 pm Post subject:
|
|
|
I went ahead and bread boarded this up and after fiddling with resistors for a while I think I've got something. It tracks reasonably well with my ms 10 now. The lowest note and the highest note are perfectly in tune with a little bit of variation in the middle octave. Obviously it's not perfect but it is definitely better. I'm not sure why it is deviating in the middle octave though. Any thoughts? |
|
Back to top
|
|
|
Citezyne
Joined: Jan 09, 2015 Posts: 24 Location: Australia
|
Posted: Sat Jan 10, 2015 8:09 am Post subject:
|
|
|
nicolas3141 wrote: | Yes, there are three main approaches to powering audio circuits from a single 9V battery (or any single ended supply).
1. Use a voltage divider to create a midpoint voltage, buffer it with a spare op-amp, then use this as your 0V reference throughout your circuit. The resistors can be large (50-100K). This is a good way to do it if you have a spare op-amp available.
2. Use a voltage divider to create a midpoint voltage, buffer it with capacitors, then use this as your 0V reference throughout your circuit. The caps need to be largish (10-1000uF) and the resistors smallish (1-10K). This usually works very well, but can create an added drain on the battery. If you want to have a power status LED this can be combined with the voltage divider as I did in the bleeper circuit to enhance the performance.
3. Use separate voltage dividers throughout the circuit wherever you need a 0V reference. This works well for smaller circuits and used to be the preferred approach for discrete transistor circuits. It reduces the risk of unforeseen feedback loops via the 0V connection which can occasionally lead to odd behaviour in some circuits.
Nicolas |
Hi again,
I'm curious to know, is there a formula to work out the resistor and cap sizes? I'm keen to put together a power supply like this on a bread board to play around more with some of your other designs. Mostly I'd use a 9v battery or a 12 volt PC PSU supply.
Also working on your simple bleeper using 2 TL074's however I don't have the 750r resistor or the 33k ones so have to wait till payday for them.
Love your work, super simple for a beginner like myself, biggest I have built is an 8 step APC. |
|
Back to top
|
|
|
nicolas3141
Joined: May 25, 2007 Posts: 185 Location: Christchurch, New Zealand
|
Posted: Tue Jan 13, 2015 3:50 pm Post subject:
|
|
|
If you are wanting to go with option 2 - two resistors and a cap to create a 0V reference - then a rule of thumb would be resistors an order of magnitude smaller than the resistors in your circuit and the cap at least an order of magnitude (or two) bigger than any caps in the circuit. But option 1 is much better if you can buffer you 0V reference with an op-amp.
Nicolas |
|
Back to top
|
|
|
Citezyne
Joined: Jan 09, 2015 Posts: 24 Location: Australia
|
Posted: Wed Jan 14, 2015 4:55 am Post subject:
|
|
|
nicolas3141 wrote: | If you are wanting to go with option 2 - two resistors and a cap to create a 0V reference - then a rule of thumb would be resistors an order of magnitude smaller than the resistors in your circuit and the cap at least an order of magnitude (or two) bigger than any caps in the circuit. But option 1 is much better if you can buffer you 0V reference with an op-amp.
Nicolas |
I would use the op amp version as recommended, I have a few TL0XX lying around that would suit the job.
Thank you again for your help, your simple Designs gave me hope when i felt that all hope was lost!
Keep up the Awesome work! |
|
Back to top
|
|
|
enomys
Joined: Dec 19, 2010 Posts: 11 Location: italy
|
Posted: Wed Feb 10, 2016 3:52 pm Post subject:
|
|
|
I did it to use it as a second oscillator with my Korg Ms10 and it works good in the range between C1 and C2, but between C2 and C3 is so detuned.. how can I do? thanks so much |
|
Back to top
|
|
|
enomys
Joined: Dec 19, 2010 Posts: 11 Location: italy
|
Posted: Thu Feb 11, 2016 10:55 am Post subject:
|
|
|
with a TL072 the tracking is good... |
|
Back to top
|
|
|
nicolas3141
Joined: May 25, 2007 Posts: 185 Location: Christchurch, New Zealand
|
Posted: Mon May 23, 2016 1:14 pm Post subject:
|
|
|
Yes, this circuit works well with +/-4.5V from a 9V battery and virtual ground type setup, just make sure to either buffer the virtual ground with a third opamp or put a decent sized cap on it to keep it stable during the sawtooth switch.
Another question - has anyone added hard sync between two of these? There are a few different ways to add sync to a sawtooth, but I haven't tried adding to this circuit, not sure what would work best.
Thanks,
Nicolas |
|
Back to top
|
|
|
danfan
Joined: May 26, 2008 Posts: 7 Location: chicago, il
|
Posted: Mon May 23, 2016 10:58 pm Post subject:
|
|
|
Bear in mind that I have little understanding of what I'm doing. What I did:
I was able to coax some OK hard sync using ken stone's gate-to-trig circuit with its output fed to the gate input of an NTE467 n-channel JFET. I tied the gate input of the JFET to the negative rail via an 18k resistor (a la the mfos vco value) to keep the JFET open/timing cap working properly. Then I connected the JFET's drain and source to either side of the oscillator's timing cap. I keep going back and forth between 10n/1n caps for ken's circuit to shorten the pulse time/get the best response.
I was able to coax sync at audio rate from tri and dirty sine, but in low audio/sub audio rate I was only able to use a hard edge.
Side note: I'm using this to consistently trigger the osc of a kick drum from zero. I get a click on reset (clicks every time is better than clicks some of the time!). Shortening the pulse time was where I was looking to diminish the click but still get the reset...unless it would be easier to just throw a high cutoff RC low pass on the output.
Better ways of sync'ing this little guy? |
|
Back to top
|
|
|
blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
|
Posted: Fri Jun 03, 2016 3:36 pm Post subject:
|
|
|
In http://electro-music.com/forum/post-419924.html#419924 sharkattackeddie posted a question re. the oscillator in this thread. I can not merge that message into this thread, but it would have been .. oh well .. maybe someone can help sharkattackeddie :-) _________________ Jan
also .. could someone please turn down the thermostat a bit.
|
|
Back to top
|
|
|
nicolas3141
Joined: May 25, 2007 Posts: 185 Location: Christchurch, New Zealand
|
Posted: Sun Jun 05, 2016 10:11 pm Post subject:
|
|
|
The issue mentioned with bad sound from a power supply choice is hard to diagnose without more info, but here are some suggestions:
- it could be insufficient buffering caps on the 0V virtual ground. If it is getting pulled one way or the other by a couple of volts that may not matter so much on a higher voltage supply, but on a lower voltage supply it may cause you to run out of headroom.
- it could be that the bad sounding power supply is particularly noisy, some just are not well suited to audio use. Adding regulators, caps, etc can help, but some switchmode power supplies designed for charging batteries, etc are almost beyond redemption.
- you could have a ground loop problem with the power supply and the oscillator and the amp interacting. Experiment with a battery powered headphone amp and avoiding all mains powered equipment such as mixers/effects/amps/computers/oscilloscopes/etc. See if it still does it when the oscillator is the only mains powered module in the whole system.
Nicolas |
|
Back to top
|
|
|
sharkattackeddie
Joined: May 24, 2016 Posts: 6 Location: UK
|
Posted: Mon Jun 06, 2016 2:44 am Post subject:
|
|
|
nicolas3141 wrote: |
- it could be insufficient buffering caps on the 0V virtual ground. If it is getting pulled one way or the other by a couple of volts that may not matter so much on a higher voltage supply, but on a lower voltage supply it may cause you to run out of headroom.
Nicolas |
I didn't use a capacitor in my power supply splitting, just two 100k resistors. Could you recommend the value of cap to go in and where it should go? I reckon I could probably still squeeze it onto the vero board I used to build the circuit on. |
|
Back to top
|
|
|
nicolas3141
Joined: May 25, 2007 Posts: 185 Location: Christchurch, New Zealand
|
Posted: Tue Jun 07, 2016 12:59 am Post subject:
|
|
|
Ok, I would try switching to somewhat smaller resistors, say 10-22K, and in parallel with both resistors put an electrolytic cap, say 33-100uF. If you can still hear some noise, you could also add in parallel small ceramic caps of 100n, to filter the high frequency noise that the electrolytics are not so good at.
If you have space problems on the pcb you can stack the components into one set of holes, for example by putting the electrolytics on one side of the board and the resistors on the other side.
Nicolas |
|
Back to top
|
|
|
krabbencutter
Joined: Aug 17, 2018 Posts: 1 Location: Germany
|
Posted: Sat Jan 19, 2019 5:52 am Post subject:
|
|
|
Ojd wrote: | I've encountered some problems with the osc: [...]
2. When I connect osc output into CGS DC mixer, turning its corresponding level causes osc to change its pitch. Maybe output resistor (1k) has something to do with it? Or its capacitor in the osc? Also i used 358 chip for mixing, maybe higher quality opamp will cure it?
By the way i've used 104 (which is 100nf), and its a bit low. But i still get 3,5 octaves. If I put 47 nF it'l be higher an octave, right? |
First of all, thanks for this great little VCO It's working great so far.
But I'm encountering the same issue as Ojd. When I run the signal into my VCF (René Schmitz's MS-20 VCF) turning the Frequency knob will affect the Oscillator's pitch
Any idea what might cause this?
Update:
Raising the output resistor R4 of the VCO seemed to do it in my case. 10k already made a noticeable improvement. In the end I've settled on 47k. The issue was barely noticeable from 22k onwards but it was only above 33k where I felt like the pitch instability was gone completely. |
|
Back to top
|
|
|
wackelpeter
Joined: May 05, 2013 Posts: 461 Location: germany
Audio files: 10
|
Posted: Mon Feb 11, 2019 3:47 am Post subject:
|
|
|
As someone mentioned before i guess this circuit would greatly benefit from buffering it's output. _________________ https://soundcloud.com/bastian-j |
|
Back to top
|
|
|
Blacksheep32
Joined: Oct 22, 2019 Posts: 1 Location: Cleveland
|
Posted: Fri Nov 01, 2019 7:05 am Post subject:
White LEDs issue? |
|
|
I know this is sorta a dead post, but has anybody had success using White LEDs with this design? I made a dual saw with this design, my Red LED version is humming along, but my White LED runs for a second or so and then peters out.
Thanks again Nicolas for posting this, I found your designs via Kristian Blasol's youtube series! |
|
Back to top
|
|
|
|