Chuck D. Bones
Circuit Wizard
Absolutely! That's what I used.
This Week on the Breadboard: MOSFET Driver Redux
- Thread starter Chuck D. Bones
- Start date
jubal81
Well-known member
I got this up in the Wish List. Vote and cross your fingers!
cooder
Well-known member
Last boxing ups of the year, and it's a goodie.... this thing rips!
Cheers @Chuck D. Bones here's my version of the MOSFET Redux, called Cowpoker. And it has some buzz to it indeed, it screams and has a ton of gain available, harmonics pinch easily of the board. Noice one!
Since I allowed for compensation cap (used 33 pF) I tried TL071, CA 3130 and I ended up using a Russian KR1408B supposedly workalike of LM308 chips. All sounded great but the Russian one had maybe a bit less noise on high gain, surprisingly.
Cheers @Chuck D. Bones here's my version of the MOSFET Redux, called Cowpoker. And it has some buzz to it indeed, it screams and has a ton of gain available, harmonics pinch easily of the board. Noice one!
Since I allowed for compensation cap (used 33 pF) I tried TL071, CA 3130 and I ended up using a Russian KR1408B supposedly workalike of LM308 chips. All sounded great but the Russian one had maybe a bit less noise on high gain, surprisingly.
Chuck D. Bones
Circuit Wizard
SWEET! I didn't know they had opamps in Russia. Try an NE5534 if you have one. The LF356 on my breadboard is plenty quiet.
Where did you end up setting the Gain Trim?
Where did you end up setting the Gain Trim?
cooder
Well-known member
I do have an 5534 will throw that in. I have the gain trim pretty low, because my age bracket doesn't cope anymore with too much of that gainy stuff... lol... It has plenty of gain as is anyway.
Great sounding for sure.
I got those Russian opamps outta curiosity and have them in some Rat style circuits. Do I hear a difference, I dunno, sounds good though and a bit of exotic fun why not. Love some of the Russiabn tubes. so why not opamps as well when it fits.
Great sounding for sure.
I got those Russian opamps outta curiosity and have them in some Rat style circuits. Do I hear a difference, I dunno, sounds good though and a bit of exotic fun why not. Love some of the Russiabn tubes. so why not opamps as well when it fits.
Chuck D. Bones
Circuit Wizard
Maybe try a bigger compensation cap on the 5534. Where did you get the YR1408B?
What do you think of the BASS & TREBLE control ranges? Are they OK or would you tune them differently?
What do you think of the BASS & TREBLE control ranges? Are they OK or would you tune them differently?
cooder
Well-known member
What size comp cap would you recommend? 100pF?
Bass and treble seems both quite useful, so I find good range in there. Treble below 10 o'clock is a bit dull for me but it's good that it has a wide range, nothing wrong with that.
I got the Russian chips here:
https://www.ebay.com/itm/144257700303?hash=item21966dd1cf:g:YhoAAOSwMNxXVml-
Bass and treble seems both quite useful, so I find good range in there. Treble below 10 o'clock is a bit dull for me but it's good that it has a wide range, nothing wrong with that.
I got the Russian chips here:
https://www.ebay.com/itm/144257700303?hash=item21966dd1cf:g:YhoAAOSwMNxXVml-
Chuck D. Bones
Circuit Wizard
100pF is a good start. The other thing to try is a larger feedback cap (C3 on my sch). My gut feel is the NE5534 and LT071 aren't noisier, they just have more bandwidth.
The eBay seller implies they're equivalent to LM308, but without a datasheet, who knows?
The eBay seller implies they're equivalent to LM308, but without a datasheet, who knows?
cooder
Well-known member
I just downloaded the data sheet from Russian chip . It does make even less sense than normal to me... lol...
https://pdf1.alldatasheet.com/datasheet-pdf/view/1205140/KWAZAR/KR140UD1408B.html
https://pdf1.alldatasheet.com/datasheet-pdf/view/1205140/KWAZAR/KR140UD1408B.html
Chuck D. Bones
Circuit Wizard
Turns out I had a translated datasheet for that part. Slew rate is 0.05V/μs, which is slow even by LM308 standards. Gain and bandwidth are also low numbers. Explains the "low noise" performance you're observing. If you like the tone, who am I to judge?
cooder
Well-known member
Thanks for digging those up @Chuck D. Bones !
Chuck D. Bones
Circuit Wizard
Finally got mine boxed up. Thanks to Stephan for the board and Brett for the beautiful box artwork.
The toggle switch pads on the board didn't line up with the box artwork, but that was easily fixed by wiring the switch to the board instead of soldering it directly. I had to mount the board higher, so I used solder lug pots and connected the pots to the board with some stiff solid wire.
This board has a shit-ton of gain. I run mine with the Gain Trim turned all the way down.
This is a v1 board. I did the "squeal reduction mod." It helped, but did not completely eliminate the squeal at high GAIN & VOLUME settings. I have some V2 boards and will see how they do.
The relay controller runs the Coda Effects code which toggles the relay when the stomp switch is released. I worked around that by swapping the switch with its 10K pull-up resistor. Now it toggles the relay when the switch is pressed. It got me to thinking about modding the code. Then I came to the conclusion that a microcontroller is complete overkill here and the 555-based relay driver is a better way to go when we don't need a bunch of fancy features. Below is a slight mod to the PedalBCB basic relay bypass. The open-collector DISCHARGE output (pin 7) has greater current sink capabilities than the the OUTPUT (pin 3), so I use that to drive the relay. This circuit is compatible with 4.5V, 5V & 9V relay coils simply by changing R4. C1 does not need to be film; aluminum and tantalum caps have a smaller footprint. The only time this circuit needs a regulator is if someone wants to run the pedal on something higher than +15V.
BTW, there is nothing magic about the values of R1-R3 & C1. I tried 1M, 100K, 100K & 220nF and they work great.
The toggle switch pads on the board didn't line up with the box artwork, but that was easily fixed by wiring the switch to the board instead of soldering it directly. I had to mount the board higher, so I used solder lug pots and connected the pots to the board with some stiff solid wire.
This board has a shit-ton of gain. I run mine with the Gain Trim turned all the way down.
This is a v1 board. I did the "squeal reduction mod." It helped, but did not completely eliminate the squeal at high GAIN & VOLUME settings. I have some V2 boards and will see how they do.
The relay controller runs the Coda Effects code which toggles the relay when the stomp switch is released. I worked around that by swapping the switch with its 10K pull-up resistor. Now it toggles the relay when the switch is pressed. It got me to thinking about modding the code. Then I came to the conclusion that a microcontroller is complete overkill here and the 555-based relay driver is a better way to go when we don't need a bunch of fancy features. Below is a slight mod to the PedalBCB basic relay bypass. The open-collector DISCHARGE output (pin 7) has greater current sink capabilities than the the OUTPUT (pin 3), so I use that to drive the relay. This circuit is compatible with 4.5V, 5V & 9V relay coils simply by changing R4. C1 does not need to be film; aluminum and tantalum caps have a smaller footprint. The only time this circuit needs a regulator is if someone wants to run the pedal on something higher than +15V.
BTW, there is nothing magic about the values of R1-R3 & C1. I tried 1M, 100K, 100K & 220nF and they work great.
Last edited:
cooder
Well-known member
Finally got around putting a demo video for this together, thanks again for Dave pumping out all these fab circuits and tweaks!
Playing in the video thanks to my friends Warren Mendonsa from Auckland, also know under the moniker blackstratblues. Check out his music, he's an amazing player.
And yes, I'm still using the Russian chip in there...
Playing in the video thanks to my friends Warren Mendonsa from Auckland, also know under the moniker blackstratblues. Check out his music, he's an amazing player.
And yes, I'm still using the Russian chip in there...
owlexifry
Well-known member
Chuck D. Bones
Circuit Wizard
Can you hear the diff with the Russian chip? I wouldn't think so. We had a problem with oscillation on that board at high GAIN settings, how did you deal with that?
cooder
Well-known member
I really dunno how much difference my bleeding ears heard with the Russian chip or not. It just sounded good too and it seemed a good circuit to put it in, as I had a few. Maybe it has a bit less bandwidth that actually helps in such a high gain circuit? But as said if there was a difference it was hairs width.
I ended up using a lower resistance gain pot (A100k) as it has anyway sh*tloads of gain. That seemed to help avoiding oscillation.
I wouldn't mind redesigning the board for the I/O boards and see if we can get the oscillation with better parts placement sorted.
Chuck D. Bones
Circuit Wizard
Reducing the GAIN (DRIVE) pot is not a bad idea. Like you say, no shortage of gain. In any case, we should have another bash at a board layout.
bluedmc777
Active member
Any chance for a Boneyard Cattle Driver in the future?
bluedmc777
Active member
Let’s Just take a moment and acknowledge that Chuck thumbs upped the boneyard cattle driver lol. 
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