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nosi0
Gold Member
Netherlands
511 Posts |
 Posted - 01/20/2010 : 21:07:57
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So i started doing my homework on the flip-flop circuits, reading loads of articles about them and started to understand exactly how it work. after that experimented by using a multimeter and measuring the voltage on the transistors when you switch. Gives you a great idea of whats really going on. This led me to the idea of making my own boss true bypass mod, so after more soldering and experimenting ive hit a wall.
What i need for my mod to work is rather simple. something that produces a short voltage spike on one wire and routes a ground signal to the other wire, when the original Boss switch is tapped. BUT the next time the switch is tapped the voltage spike has to be on the other wire and the ground on the wire the spike was on earlier.
In theory the Flip Flop ciruit should be able to produce what i'm looking for, or with some significant re-wiring anyway. ive been experiemtning with this for quite a while with little success.
This is how i can best explain it. its not really a spike just nead anything greater than 6.75 volts for a fraction of a second. the time period can be longer but not that the voltage spike stays on until the switch is pressed again.
This is what parts i think i should disconnect from the CS-3 (labeled in read). and i think i'll need a green jumper wire to ensure that the effect is on. In my mind i want to cut more stuff out but i'm not sure what the function is of the resistors and caps to the right towards the output. i guess there there for a reason. If somebody sees somthing else that i can remove please tell me.
This is my current theory for what i need but i haven't been able to build it yet. i just copied the values from the original flip flop so i will still need to recalculate those possibly with help. I think it might need another 2 diodes but i haven't figured out where. I just looked at it and i don't see what those diodes are doing the ones heading towards the FET transistors. well i'll see what you guys think.
Nosi
P.S. sorry for those who like the CS-3, she's my guinea pig, a great one at that  . |
Edited by - nosi0 on 01/20/2010 21:14:13 |
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Scarymonsta
Bronze Member
United Kingdom
90 Posts |
Posted - 01/20/2010 : 21:24:33
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The schematic you show with the green wire would mean that the effect is always on, pressing the footswitch would just switch the clean signal in and out - so you would have compressor effect only or compressor and clean signal (but as there is nothing to attenuate the clean signal this may not sound too good...)
Do not remove any other components Q4 and Q5 determine which signals pass through to the output.
Can you explain exactly what effect you wish to achieve, then I can help you a little more...
do you want to true bypass switch the entire compressor?
Chris |
Edited by - Scarymonsta on 01/20/2010 21:27:31 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 01/20/2010 : 21:28:50
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I'm guessing you using a latching relay that requires a momentary drive signal that changes polarity to turn it on and off? I tried this a while ago... couldn't get it off the breadboard.
http://www.bossarea.com/forum/topic.asp?TOPIC_ID=6810
There has to be an elegant solution to this, but I haven't had time to work on it. |
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nosi0
Gold Member
Netherlands
511 Posts |
Posted - 01/20/2010 : 21:29:13
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Well i found a relay that works perfectly for the situation. its a latching type so it only needs a little shot of voltage to click into a positions. the only problem is the polarity applied to the coil needs to be switched everytime to make the switch, switch.
So all the switching happens outside of the schematic i can wire that up. thats why i removed Q4 and Q5. I thought by bypassing Q5 and cutting Q4 out i would ensure that the effect is always on. i left the right 1M resistor next to Q4 there as i figured its normally there when the signal is on.
I hope this helps i'm not great at explaining things  |
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nosi0
Gold Member
Netherlands
511 Posts |
Posted - 01/20/2010 : 21:34:30
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I knew you'd be the one to help Laurie! I missed that topic, the title probably scared me  . I was inspired by the topic with you me, and andreas (stinkfoot) and a few others disgusing his attempts to install a dpdt or 3pdt into a boss pedal without success. which led us to talking about relays. and your spot on about the latching relay. i got a different schematic than you though but comes down to the same thing. I got a couple of TQ2-L 9V, though i think that TQ2-l 5V would be easier to implement but thats not the main problem. |
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Scarymonsta
Bronze Member
United Kingdom
90 Posts |
Posted - 01/20/2010 : 21:36:08
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Laurie, did you use a 4013 on your breadboard - I was thinking along the D-type lines but I don't think its quite the way to go...??
I'll have to have a quick peek a latching relay Nosi0 and give it a bit more thought.. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 01/20/2010 : 21:43:25
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quote:
Originally posted by nosi0
I knew you'd be the one to help Laurie! I missed that topic, the title probably scared me . I was inspired by the topic with you me, and andreas (stinkfoot) and a few others disgusing his attempts to install a dpdt or 3pdt into a boss pedal without success. which led us to talking about relays. and your spot on about the latching relay. i got a different schematic than you though but comes down to the same thing. I got a couple of TQ2-L 9V, though i think that TQ2-l 5V would be easier to implement but thats not the main problem.
Yeah, you have the latching version where you change polarity on the same pair of pins to unlatch it. I went for the one that had a separate set of pins for unlatch. Same idea, whatever works for one will work for the other with a couple of diodes or transistors to convert the drive signal.
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nosi0
Gold Member
Netherlands
511 Posts |
Posted - 01/20/2010 : 21:45:37
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Do you think what i drew in the schematic of the control part of the relay will work. sans the diodes leading to the FET transistors?
Your schematic suggests you are using a latching switch to control the circuit or am i imagining things? |
Edited by - nosi0 on 01/20/2010 21:46:49 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 01/20/2010 : 21:46:10
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quote:
Originally posted by Scarymonsta
Laurie, did you use a 4013 on your breadboard - I was thinking along the D-type lines but I don't think its quite the way to go...??
I'll have to have a quick peek a latching relay Nosi0 and give it a bit more thought..
Yeah, there is a bit of text that's easy to miss under the diagram...
"I have a circuit based on a D-type CMOS flip flop (4013) that will convert the continuous signal at A and B to a pulse. But for some reason it fails when connected to a live pedal - the flip-flop in the pedal seems to be both on and off momentarily and that confuses the convertor."
Interestingly in the real world with the pedal there appears to be an "undefined" instant when the flip-flop is in transition that confuses the CMOS logic.
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 01/20/2010 : 21:49:06
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quote:
Originally posted by nosi0
Do you think what i drew in the schematic of the control part of the relay will work. sans the diodes leading to the FET transistors?
Your schematic suggests you are using a latching switch to control the circuit or am i imagining things?
Don't know about the FETs... will give it some thought.
I'm trying to use the flip-flop output - just like you are  |
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nosi0
Gold Member
Netherlands
511 Posts |
Posted - 01/20/2010 : 21:49:42
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damn that sucks. so that means you are using a latching switch then? what if you were to use a momentary switch to drive the circuit?
Considering that stuff is already inside there might aswell use it |
Edited by - nosi0 on 01/20/2010 21:50:27 |
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Scarymonsta
Bronze Member
United Kingdom
90 Posts |
Posted - 01/20/2010 : 21:55:02
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| Is a better idea to use a non-latching DPDT relay and drive it with a FET/bipolar, using the signal at the R21/R22 junction to drive the base (through an R)/gate, and hook the relay contacts to the pedal input and output, and short across the drain and source of Q4 and 5?? |
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nosi0
Gold Member
Netherlands
511 Posts |
Posted - 01/20/2010 : 21:59:28
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I have to think about the first part but if you short Q5 then doesn't the signal bypass the effect and head straight for the output. I think you should disconnect Q5 and jump Q4 like you also suggested.
(illogical numbering of those transistors haha.)
Here the diode placement seems more logical. EDIT: crap nevermind then it will never make contact with the ground. |
Edited by - nosi0 on 01/20/2010 22:04:47 |
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Scarymonsta
Bronze Member
United Kingdom
90 Posts |
Posted - 01/20/2010 : 22:16:00
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Yep you're right  scratch my comment about Q5 -was getting a bit ahead of myself... |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 01/20/2010 : 22:26:49
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What I've done for the successful true-bypass mods I've done is use an ultra-miniature DPDT standard relay and drive it from the flip-flop through a BJT. The relay I used draws about 20mA "on" which was acceptable on a powered pedal-board. It is almost OK on battery...
Anyway, all it took was the DPDT relay, a PNP BJT, a couple of resistors and a fly-back diode. Low parts count and an easy build.
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 01/21/2010 : 13:16:43
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Hi nosi0
Just a little off topic.
What package do you use to draw your schematics, & what component library file?
Very tidy work there nosi0.
Regards Dr. Bob |
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Nosi's Boss true bypass mod. (work in progress)
