hi everyone,
1. need help prototype schematic CD4049 low level guitar signal cascade multi-stage soft clipping preamplifier.
2. nobody wants to utilize all six stages of cascading but why? noisy? battery dead too soon?
3. wouldn't delightful sound come from gradually boosting signal through many stages to obtain soft clipping progressively via multi-stages cascade topology?
4. web shows up to three stages but no more - the rest of the inverters are idle.
5. isn't small gains per stage better to arrive at the final soft clipping arena? doesn't this boost conservative approach broaden spectrum per stage?
6. or does this invite excessive guitarist controls that would confuse and frustrate the guitarist? at minimum would need a pot or trimmer per each stage feedback - and these umbilicals would crosstalk in the physical wiring birdnest?
7. figure on 2mA per inverter railed by two separate lithium DC supplies, 1.5V, totalizes to 12mA much too excessive?
8. any help much appreciated - will utilize surface mount CD4049 as it is significantly tinier than the DIP
1. need help prototype schematic CD4049 low level guitar signal cascade multi-stage soft clipping preamplifier.
2. nobody wants to utilize all six stages of cascading but why? noisy? battery dead too soon?
3. wouldn't delightful sound come from gradually boosting signal through many stages to obtain soft clipping progressively via multi-stages cascade topology?
4. web shows up to three stages but no more - the rest of the inverters are idle.
5. isn't small gains per stage better to arrive at the final soft clipping arena? doesn't this boost conservative approach broaden spectrum per stage?
6. or does this invite excessive guitarist controls that would confuse and frustrate the guitarist? at minimum would need a pot or trimmer per each stage feedback - and these umbilicals would crosstalk in the physical wiring birdnest?
7. figure on 2mA per inverter railed by two separate lithium DC supplies, 1.5V, totalizes to 12mA much too excessive?
8. any help much appreciated - will utilize surface mount CD4049 as it is significantly tinier than the DIP
This would more properly be placed in Instruments and Amps where someone might be able to help you.. 
Basically you're suggesting making apple pies from tomatoes (both red and round, right?) and then saying it doesn't taste right.
If you're going down that path, you might try a 4069 which is closer to linear than the buffered 4049. There are a lot of crystal oscillators using the 4069.
G²
What I was suggesting is to try adding an extra inverter stage onto the first 2 or 3 and see if the noise level is acceptable. If the gains are set low in each stage, it may be alright. Depends on one's taste whether it's ''right''. CD 4069, being closer to linear, possibly matters less in an overdrive circuit which is ultimately non linear.
So go to a comparator and play with different values of hysteresis. It will be very non linear if that's the goal.
G²
Yes, a comparator circuit would be very non-linear, hard clipped .It would be more of a fuzz pedal than an overdrive/distortion circuit. I built a 2 stage 4049 (based on Craig Anderton circuit) and it sounds pretty decent, overdrives pretty early so with some lower gain on individual stages and some additional tone shaping per stage,3 or 4 stages will likely sound pretty good. With 6 stages it probably would sound a lot more like a fuzz pedal too.
maybe cd4049 low noise version IC would be a better avenue to go?
does it exist "low noise version", equal or better?
each stage is fet in the cd4049 - separate discrete low noise jfet like 2sk170 would be equivalent to cascading inverters of cd4049?
otherwise maybe noise can be attenuated by tempering inverter stage gains, like under 5 per stage?
does it exist "low noise version", equal or better?
each stage is fet in the cd4049 - separate discrete low noise jfet like 2sk170 would be equivalent to cascading inverters of cd4049?
otherwise maybe noise can be attenuated by tempering inverter stage gains, like under 5 per stage?
No such thing as a low noise CD4049, it is an digital inverter IC that just happens to work as mediocre inverting amplifier. Now you could try a few different vintages and vendors and see if any just happen to be quieter. Note that the CD4049 uses complementary mosfets, not jfets - not in any sense equivalent.
Build something and see if you can get it to work.
References:
http://www.generalguitargadgets.com/richardo/distortion/
http://www.muzique.com/schem/tubesnd.gif
Build something and see if you can get it to work.
References:
http://www.generalguitargadgets.com/richardo/distortion/
http://www.muzique.com/schem/tubesnd.gif
Largely irrelevant, these devices were not designed as anything but fast switches - not intended for linear use, but with care you may be able to get things quiet enough to do the job. The geometry/doping of those mosfets is optimized for speed and low power consumption - the things that matter for the intended application.
Don't run the stages at too high a current. If you run them near 3V, the gain is higher, the noise and bandwidth are lower. Connect gates in parallel for lower noise. I've used up to 12 (two packages piggybacked). You must use an "unbuffered" part, usually with a U suffix as in CD4069U. The only problem running low current is that you can't drive much. Use an opamp or JFET as a buffer. You can use one inverter in a package to set the bias for the other gates. Just connect input to output and that voltage can be used to bias the other gates.
Don't use a voltage regulator right on the supply pin. Use a higher voltage like 5V and then use an RC network between the regulator and IC. Use the resistor to set the current, something between 1K and 100K.
The CD4007 can also be used but you have to connect the MOSFETs up to make inverters. You can also connect the 4007 up to make NOR or NAND gates for more distortion.
Don't use a voltage regulator right on the supply pin. Use a higher voltage like 5V and then use an RC network between the regulator and IC. Use the resistor to set the current, something between 1K and 100K.
The CD4007 can also be used but you have to connect the MOSFETs up to make inverters. You can also connect the 4007 up to make NOR or NAND gates for more distortion.
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Old National AP note: http://www.qsl.net/l/lu7did/docs/QRPp/TTL_CMOS As Linear Amplifier_AN-88.pdf
Here's some data I took on a 4069U with all 6 inverters biased linear. There is a lot of variation between parts.
3V 25uA
5V 2.3mA
6V 5.0mA
7V 8.3mA
8V 12.5mA
9V 17mA
10V 22mA
12V 37mA
14V 44mA
15V 47mA
The inverters look more like tubes at low voltages. At higher voltages the top and bottom of the waveform looks extremely rounded unless you use lots of feedback. You can easily get a gain of 10 (20dB) per stage with feedback.
3V 25uA
5V 2.3mA
6V 5.0mA
7V 8.3mA
8V 12.5mA
9V 17mA
10V 22mA
12V 37mA
14V 44mA
15V 47mA
The inverters look more like tubes at low voltages. At higher voltages the top and bottom of the waveform looks extremely rounded unless you use lots of feedback. You can easily get a gain of 10 (20dB) per stage with feedback.
@ alayn91, thanks for posting. The CA3600 has the same pinout as the CD4007. It's not clear if there is actually any difference in the parts. The CA3600 may be impossible to find.
The pdf file shows how gain, bandwidth and current change at different supply voltages. 47K is pretty low impedance. At low currents it needs to be much higher, something like 1 to 10 Megohms.
The attached file below shows some design ideas.
The pdf file shows how gain, bandwidth and current change at different supply voltages. 47K is pretty low impedance. At low currents it needs to be much higher, something like 1 to 10 Megohms.
The attached file below shows some design ideas.
Attachments
Very good chip suggestion, Loudthud. The Craig Anderton circuit was a bit too limited , literally I found it quite a compressed sound with the 4049.
The 4007 has some access to individual Mosfets, which I had been meaning to fool around with, but became a backburner project. Like you said you need to build up the inverter etc, but allows one to ''build down'' to a simple common source amp stage, and also add Drain limiting on individual stages, which could be interesting. So maybe time to go back to the breadboard and see what I could come up with.
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