this is the project i built, a simple, i mean SIMPLE tremolo.
http://www.techniguitare.com/HOTPROJETS/Tremolo2Transistors.pdf
i figured, what the hell, and built it according to this vero i worked up, which i believe to be right
(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/frogtrem_zps8629edd1.gif)
and here's the schemo:
(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/2trantrem_zpsc9c16593.png)
it lights up the led, and if i cover the circuit with my hand, i can hear the volume go up, but i'm not getting any oscillation, i don't think.
i know NADA about this stuff, i'm a fuzz guy.. anybody got any ideas?
or should i just flush this project to the bottom of the "oh well" pile?
all the resistors /caps are specced values, i don't have bc 547's, so tried various npn's, no luck tho.
thanks!!
yah, i added reverse polarity, some filtering, that's about it, so the part numbers may be wack. ;) this was just something to work from. wasn't meant for anyone to use, so i didn't clean it up at all. :)
From page 4 of the forum thread on this project;
Quoteil suffit de changer la 220k par une 100k, celle qui est a coté de on/off , pour faire démarrer l'oscillation !
Change the 220K resistor to 100K to get the oscillation going.
Quoteon peut changer la 1k5 qui est a coté du 100uf pour une 2k2
Change the 1K5 next to the 100uF to 2K2.
Quoteplus de patate a l'oscillation avec un bc549c
Better oscillation beat with a BC549C.
Quoteet si la led eclaire trop changer la 1k5 par une 3k voir 4k
If the LED is too bright, change the 1K5 to 3K or 4K.
Quotevoila ca fonctionne , pas encore tester sur du son !
Voila, it works. Not tested with sound yet.
Quote from: digi2t on February 06, 2013, 08:01:59 PM
From page 4 of the forum thread on this project;
Quoteil suffit de changer la 220k par une 100k, celle qui est a coté de on/off , pour faire démarrer l'oscillation !
Change the 220K resistor to 100K to get the oscillation going.
Quoteon peut changer la 1k5 qui est a coté du 100uf pour une 2k2
Change the 1K5 next to the 100uF to 2K2.
Quoteplus de patate a l'oscillation avec un bc549c
Better oscillation beat with a BC549C.
Quoteet si la led eclaire trop changer la 1k5 par une 3k voir 4k
If the LED is too bright, change the 1K5 to 3K or 4K.
Quotevoila ca fonctionne , pas encore tester sur du son !
Voila, it works. Not tested with sound yet.
COOL!!
thanks dino, i'll give all that stuff a try, and report back. appreciate it bro!! ;)
nope. no diff at all.
voltages look like they SHOULD be ok to me, but then, i don't know about oscillators..
batt: 9.08
after 220r "noise" resistor : 8.83
q1
c 4.17
b 1.33
e .75
q2
c 8.83
b 5.14
e 4.55
led + 1.85
pretty sure this thing would work if i could get the led to flash! ;) :icon_mrgreen:
Posting from my phone, and can't see the whole of the schematic, but the bit I can see looks quite similar to the RG inspired oscillator that Frequency Central used in the Vibracaster.
The V'caster is VERY picky regarding transistors. It needs a hfe of at least 800 to start wiggling, and even then can be quite fussy. I've never had much luck with anything other than 547c (the 'c' is important).
Can't swear this is relevant though....... :icon_redface:
It's a phase shift oscillator.. a very tricky pony
P3 and the LDR form a voltage divider. How much change in attenuation it provides will depend on the light/dark value of the LDR, whichin turn, will depend on the illumination it receives from the LED. If the LFO and LED driver circuit are only making your LDR wiggle between 1M and 100k, you're not going to hear very much variation in volume level. You'll want the LDR to be above the value of P3 at full darkness, but drop below P3's value (47k) when illuminated.
T'were I , I start out by sticking an LED of respectable brightness/efficiency in the circuit, as is, and see just how much illumination, and change in illumination, I'm getting from the stock circuit.
As an aside, it reminds me of the What compressor, that has this whole big sidechain apparatus, and the audio path also consists of a 2-component passive voltage divider. In theory, that should be clean, clean clean, with negligible hiss.
it makes no background noise, really clean, a bit of compression. the problem is, i can get the leds to light no problem, but i can't get the oscillator to roll. they just stay lit.
when i do manage to get it to fire for a millisecond or three, it seems to sound great!
i used google translate to try and communicate, they seem to be trying to help...i'll check it out over there, and see what they suggest.
thanks for the suggestions... i'm thinking i may have to get the proper transistors... they mention nte123, which i have. bloody crummy resistors for fuzz, but maybe for this..
;)
Ah, well that's completely different. Never mind.
(http://4.bp.blogspot.com/-EouX80AUbgk/TsXmsRlkSHI/AAAAAAAAAKo/jR9NyrqrijA/s1600/imagesemily-litella-1-small.jpg)
Are you sure you have the pinouts right?
yah mark, i check any oddball things i don't use all the time (and which i keep accumulating for some reason) with my meter to see what it is and what the pinout is.
i have a gazillion transistors but NONE seem to actually work, unless i'm missing something.
i subbed out the 220k resistor for a 100k as advised, no dice. tried using a pot... at certain ranges, the led will go out for a split second, then back up it comes, loud and proud.
it looked like a pretty cool simple circuit, anyways. ;) :icon_biggrin:
Quote from: ~arph on February 07, 2013, 07:49:21 AM
It's a phase shift oscillator.. a very tricky pony
I was going to say that. it is actually a one transistor oscillator when it works right. there is a lot of information on the internet but I never got one to work in the sim. I was messing with different RC filter frequencies and even tried external excitation through a square impulse or filtered square impulse. never got this thing to work but I did get it to resonate for about 2 cycles after the impulse. it clearly had a resonant frequency but never got it to have enough gain.
Quote from: pinkjimiphoton on February 07, 2013, 05:39:45 PM
yah mark, i check any oddball things i don't use all the time (and which i keep accumulating for some reason) with my meter to see what it is and what the pinout is.
i have a gazillion transistors but NONE seem to actually work, unless i'm missing something.
i subbed out the 220k resistor for a 100k as advised, no dice. tried using a pot... at certain ranges, the led will go out for a split second, then back up it comes, loud and proud.
it looked like a pretty cool simple circuit, anyways. ;) :icon_biggrin:
I would trouble shoot it in two parts. first you need to find the sweet spot where the LED will turn off with the switch open. make R9 smaller till the Q2 base voltage drops low enough to turn off the LED. then when you connect your phase shift oscillator, any AC voltage greater than Q2 B should pass the cap and blink your LED on and off. if when you close the switch, your LED stays lit continuously, that means you must have a working oscillator since it is AC coupled by 10uf. if the oscillator is blinking the LED fast enough you might not notice it is blinking. maybe a trimmer on R9 would help you find the sweet spot? you can also decrease R10 to compensate for an oscillator that is low in amplitude but you run the risk of blowing the LED and it will only work if R9 is perfect anyway.
One observation: C3 in the schematic says 470, not 470n. Might be an error, but have you tried that?
EDIT: 470 what I don't know, if not 470n. 470p? Like I said, just an observation.
Quote from: Keppy on February 07, 2013, 11:48:10 PM
One observation: C3 in the schematic says 470, not 470n. Might be an error, but have you tried that?
EDIT: 470 what I don't know, if not 470n. 470p? Like I said, just an observation.
if you look at the parts list at the bottom of the schematic on the link in the first post, you'll find that it says 470nF x3 under the "condensateurs"
Quote from: psychedelicfish on February 08, 2013, 12:01:05 AM
Quote from: Keppy on February 07, 2013, 11:48:10 PM
One observation: C3 in the schematic says 470, not 470n. Might be an error, but have you tried that?
EDIT: 470 what I don't know, if not 470n. 470p? Like I said, just an observation.
if you look at the parts list at the bottom of the schematic on the link in the first post, you'll find that it says 470nF x3 under the "condensateurs"
Ah. Thanks for spotting that.
Well, gain is very important in phase shift oscillators. Maybe you don't have enough. I would try 1) inserting a very high gain transistor (sounds like you've already done this) and 2) increasing the value of the R1/P2 combo. More resistance there should increase the gain. If you get too much, the sine wave will distort, but if you get it working you can always turn R1 into a trimpot to dial that out.
Also, many oscillators would not work in a perfect world, because they rely on some small amount of noise to be present, which is then amplified to jumpstart the oscillation. Your power supply filtering just may be working against you here, and since there are no active devices in the signal path, I'd try taking it out just to see what happens. I'd also like to know if you wired up the switch or not, and if so, did you toggle it? The spike of current from C5 (charged up to 9v with switch open, suddenly pulled down to wiper voltage when closed) might be necessary to get the thing started. These both seem like longshot solutions compared to changing the gain, but hey, you never know!
I've built this circuit or one like it, seems a million times. it makes an ugly lumpy sine that fades at one end of the range pot, and I've never seen it with the emitter resistor/cap, and always has a collector bias resistor to b. I'd ground the e.
I'd remove R11 and put it with a higher value directly between B an C of T1.. and ground T1's emitter indeed.
Quote from: duck_arse on February 08, 2013, 10:12:31 AM
I've built this circuit or one like it, seems a million times. it makes an ugly lumpy sine that fades at one end of the range pot, and I've never seen it with the emitter resistor/cap, and always has a collector bias resistor to b. I'd ground the e.
Yes, seems you suggested the same. That bias resistor is R11.
The bias thing you guys are suggesting surprises me. Wouldn't bias from the collector effectively bypass the phase-shift network? A high enough R value would minimize this, but it still seems strange to me.
As far as grounding the emitter, the cap effectively grounds it at AC frequencies. It seems like the designer here was aiming at a more stable bias network, using a resistor divider and allowing the emitter's DC voltage to rise a bit. This way the bias current does not fluctuate as it would with bias taken from the collector. Collector biasing/emitter grounding seems worth a try if you've seen it before in these oscillators, but if there's a reason it's likely to work better I haven't understood it yet. Thoughts?
Yes that resistor should be large. Check out the EA Tremolo, the schaller tremolo or the blue warbler by Jon here. They all use pso's and all have this resistor ( ea i'm not sure )
> if i cover the circuit with my hand, i can hear the volume go up
Ultimately you need to make the LED/LDR area totally light-TIGHT. However it is handy to have it open for testing.
Yes the LED must flash, very obviously. Get that to happen and I think you are fine.
The transistor is NOT critical. I found a 1963 paper showing that hFE must be over 18, and >50 was more reliable, though >>50 becomes distorted. Since you can hardly buy a part with hFE<50 today, all you need is a "not-dead" transistor of correct polarity and known pinout. And your observed DC voltages suggest you have ample hFE (thus acceptable pinout).
220K:18K looks wrong (barely alive). 100K:18K (100K:22K is more exact) seems fine.
There are other ways to bias it, but your DC voltages look entirely suitable. Transistor is alive and collector is mid-zone of the power supply.
An oscillator is an amplifier and a feedback network. Your amplifier is fine. Look again at the feedback net, the three 470n caps and associated ~~18K resistors.
C4 must be "large". 100uFd is borderline, try 470uFd.
Usual follies: mis-wired, wrong-value part, bad solder, solder bridges. I prefer to confuse red and orange, but we all have our own favorite mistakes.
You can replace the R3 P1 string with an 18K, the ideal value. It won't vary frequency but right now you just want to see it WORK.
The R1 P2 string "should" also be 18K. I doubt 13.9K hurts; however it is really 9.9K here with loading from the buffer stage. You could change R1+P2 to 37K(39K).
BUT this circuit should NOT be this fussy. I'd still bet on a build mistake.
> I never got one to work in the sim.
It can be tough. Linear oscillators are not sure-to-start in an ideal world. In real life there is always hisss which will get it started, but it can take 1000+ cycles for oscillation to build. As it gets to decent level non-linearities slow the simulation.
Getting two damped cycles of ring does suggest insufficient gain; yet millions of these things work in a real world. Many are very crude.
> The spike of current from C5
Yes, it may be kick-start. In real life, if it is gonna oscillate, it does not need a kick, you just wait. For a 1MHz radio oscillator, as long as 0.001 seconds. For a 10Hz LFO the wait can be over a minute. Some guitar trems over-gain the oscillator for quicker start with distorted wave. Others use kick-start for near-instant start.
> Wouldn't bias from the collector effectively bypass the phase-shift network?
It actually works quite well. Note that the bias resistor will be on the order of hFE times Rc, or about 100*18K, or a couple of Megs. By itself, "large" compared to 18K network values.
But if we assume the amp's voltage gain is similar to hFe, by Miller Effect the bias resistor acts-like around 18K, and serves as a final R in the C-R-C-R... network.
See Q3 in http://www.generalguitargadgets.com/pdf/ggg_eat_sc_improved.pdf
You may steal this plan verbatim, splicing to your LED buffer at A-GGG's C4. 470nFd or 1uFd is a minor difference, use the 470nFd in your hand for now.
wow, thanks guys for all the info!!
gonna go play with this in a little bit, and try to implement some changes to get it to flash. if i can get it to flash, i know it will work, and it should sound pretty good i think.
while you guys were helping me, i was researching some stuff too.. including a simple two led flasher circuit i found..
http://www.hobby-circuits.com/circuits/led-and-light/light-flasher/770/two-flashing-leds-circuit-schematic
(http://www.hobby-circuits.com/files/770/two-flashing-leds-circuit-schematic2_med.gif)
i was thinking maybe if i used two different led/ldr's and two different colored led's it may be interesting to have them flash at slightly different rates...
ideally maybe get 'em to be slightly staggered to make it almost a phaser kinda wobble, if that makes sense.
time to get nuts... again...
this reminds me of d'astro's circuit a bit. ;)
Thanks for the info Paul!
i used that circuit in my pulse wah .
still not working.
swapped out the 220k/18 k for 100k and 22 k as paul suggested, also swapped out the 100u cap worked my way up to 1000u.
same thing.
presently have mpsa18's in there, so it's definitely got gain. but the light stays on. i've checked the vero over and over, and it's consistent with the schematic.
i'm freekin' stumped!!
gonna tear it down i guess, and start over. looked like a really fun, simple little circuit. wtf!! ;)
You should really invest in a breadboard ;D... It's like vero! But temporarily
i have one. it's lonlier than a maytag repairman usually tho. can never seem to get ANYTHING to work on it!! lol...
success!! on the breadboard, anyways...
went with a 500k linear speed pot, 1000u cap, and a plain green led which seemed to work the best.
i believe it comes down to operator error.. the pots as shown in the schematic are backwards...or at least backwards to what i was expecting. so turning the intensity pot (10k) up the led was...predictably...always lit. :icon_redface:
i'm gonna try one more time to get the vero i'd laid out working. it should work, i've looked at it til my eyes were dripping down my face (thanks to soundman rob for the psilocybes, lol) and i can't see any freaking reason whiy the layout i did shouldn't work.
that said, really nice design!! not getting any ticking at all, quiet clean and very sweet tremolo. worth a build if ya wanna super simple trem with a nice sound to it that doesn't suck all your tone away or tick.
lovin' it...
thanks everybody!! especially paul, for explaining the circuit so well even a newbe like me could understand!
> a simple two led flasher circuit i found..
The phase-shift oscillator makes a sine wave. Very smooth. Like linking a slide-pot to a bicycle crank (or engine piston).
The flasher is square-wave. HARD on/off switching.
Go ahead and build the flasher. It's fun.
But a dozen designers have sold a million trem-amps using semi-Sine wave modulation, even when it was not easy.
Yes, sine has "been done" and an on/off stutter may be a useful new tool.
And you can build them into toys, control panels, stuffed bears, fake security cameras.
Back when you could get LM3909, I liked to use them as burglar deterrents on classroom hi-fis and for back-of-the-building office windows. One D-cell would flash an LED for 2 or 3 years non-stop. An office and a classroom-hifi that had been repeatedly burgled, and a new hifi cart that begged for trouble, never got attacked once I blinkered them. The cart's LED had a sticker HIGH VOLTAGE, and nobody ever even mis-plugged a plug.
> have them flash at slightly different rates...
That 2-transistor flasher, both LEDs must flash at the SAME rate. (One on, one off.)
The dual pot is a mild annoyance. You can vary just one but the on/off won't stay 50:50. There's ways to be symmetrical with one rate pot but I don't have those notes here.
You sure can build multiple 2-transistor flashers and tune them different.
However if they are very close in rate (which may be where it gets interesting, at least to spacers), you may find they fall into sync. Hefty supply cap is a first fix. Separate R-C power filters can be necessary.
Quote from: pinkjimiphoton on February 09, 2013, 08:35:49 PM
success!! on the breadboard, anyways... newbe like me could understand!
See... breadboard. 8)
Quote from: PRR on February 10, 2013, 02:05:19 AM
> a simple two led flasher circuit i found..
The phase-shift oscillator makes a sine wave. Very smooth. Like linking a slide-pot to a bicycle crank (or engine piston).
The flasher is square-wave. HARD on/off switching.
Go ahead and build the flasher. It's fun.
i was thinking, if i can get the offset between the flashers right, it may sound a little wobbly... may be no more than twice the speed of a single trem tho.
Quote
But a dozen designers have sold a million trem-amps using semi-Sine wave modulation, even when it was not easy.
Yes, sine has "been done" and an on/off stutter may be a useful new tool.
And you can build them into toys, control panels, stuffed bears, fake security cameras.
that's kinda what i was thinking... if i could set the pots to flash opposingly, but slightly off time from each other, it may make a pretty cool sound... a hiccup, or stuttering kind of trem sound?
Quote
Back when you could get LM3909, I liked to use them as burglar deterrents on classroom hi-fis and for back-of-the-building office windows. One D-cell would flash an LED for 2 or 3 years non-stop. An office and a classroom-hifi that had been repeatedly burgled, and a new hifi cart that begged for trouble, never got attacked once I blinkered them. The cart's LED had a sticker HIGH VOLTAGE, and nobody ever even mis-plugged a plug.
:icon_mrgreen: love it!
Quote
> have them flash at slightly different rates...
That 2-transistor flasher, both LEDs must flash at the SAME rate. (One on, one off.)
pretty sure the one i'm looking at (may be different from what i posted) has a 10k pot to independently control each flasher...a long time ago, i used to use two tremolos and make 'em duke it out, and you could get some VERY psychedelic sounds out of it!! the key would be i imagine to have each trem flash at different rates, and then make a master oscillator to control the overall speed of the two of them, with whatever offset you come up with simultaneously.
is there a relatively easy way to do that do you think? seems like it could be pretty cool.
what i really liked about using the two trems (one was regular amp tremolo, the other was a little out board spring reverb unit, i think made by "marlboro"...it had reverb, trem, and "echo"...with the echo being tremolo'd reverb. when you got the two trems going the right speed, it made it delightfully easy to mask your note attacks and start sounding very frippish, even kinda backwards. it was trippy as hell!
Quote
The dual pot is a mild annoyance. You can vary just one but the on/off won't stay 50:50. There's ways to be symmetrical with one rate pot but I don't have those notes here.
You sure can build multiple 2-transistor flashers and tune them different.
i'm thinking 2 of them with 4 stages total would be the tremolo version of a phaser. may be worth exploring!!
Quote
However if they are very close in rate (which may be where it gets interesting, at least to spacers), you may find they fall into sync. Hefty supply cap is a first fix. Separate R-C power filters can be necessary.
thanks for the advice, paul!
one more thing to think about. tremolos are cool, i wonder how rg is making out with the kustom idea? ;)
Quote from: ~arph on February 10, 2013, 07:18:50 AM
Quote from: pinkjimiphoton on February 09, 2013, 08:35:49 PM
success!! on the breadboard, anyways... newbe like me could understand!
See... breadboard. 8)
lol...rub it in, arph!! lol
Quote from: pinkjimiphoton on February 10, 2013, 05:19:27 PM
that's kinda what i was thinking... it may make a pretty cool sound... a hiccup, or stuttering kind of trem sound?
Funny, that's one of the flaws I had to get rid of in the last trem I built. :icon_wink:
WELL, there's an ass for every seat, they say!! ;)
point a second ldr at the tremolo led, and use it to variable rate a second trem oscillator. dunno how you'd do it, but it sounds as though you'll try .....
needs a completely second, independent circuit to do that. :icon_mrgreen:
wanted to say, thanks for the support guys, especially paul.
i got the damned thing working. it works really good!! i was pleasantly surprised, no ticking, at least none i can hear thru my ruby.
i took paul's advice, and made the 100u electro 1,000u, and the 50k rate pot 500k..also made the 220k/18k votage divider 100k/18k, worked perfect... gives me a real nice range of speed, from a slow, almost "vibe" kinda pulse to fast enough for miserlou. i may add a switch to go between the 1,000u and maybe a 47u, so i can go from super slow to mosquito speeds.
when all was said and done..
i found the problem...after breadboarding, and building a completely different circuit..(i mean, the same circuit, different layout without the power supply filtering)..
it wasn't the wiring, it wasn't the components, it wasn't even a gosh-dang solder bridge.
THE MOTHER @#$%ING BATTERY WAS DEAD!!!!!!!!!!!!!!!!!!!!!
AY YI YI YI YI!!!
so...the DUMBEST mistake of all.
when in doubt, make sure ya gotta decent battery or power supply!!
:icon_rolleyes: :icon_redface: :icon_eek: :icon_confused: ::) :o ;D
this circuit is cool! it's tiny, works great, if you're bored, check it out!
it's buffered, and even has a slight boost when engaged... very nice!!
the 2 hardest parts of any build/building:
1. is it turned on?
2. is it plugged in?
I've fallen fowl to both this week.
lol... it looks like there was *just* enough voltage to light the led.
ay yi yi...
this thing sounds freakin' great!!
iit's a lot like d'astro's tiny trem, but without the issues.
i went for it cuz it looked EASY. and it was. once i got a good power supply!!
lol
well, now you're the go to man for tremolos, and I see a good few questions lurking .....
lol... the blind leading the blind. i don't know shit about tremolos!!
:icon_eek:
i only know when i like 'em. :icon_lol:
:icon_twisted:
and the easier, the better!!!!!
ok, here's a vero-fyed vero for this circuit, with a couple liberties taken...
made the 100u cap 1000u, and the 50k rate pot 500k...much better range of speeds, for me, anyways.
this things buffer is also a booster, and works GREAT.
i used this live last nite, and it's the only homebrew mod pedal i have built with ZERO ticking!!
anyways... enjoy. if you want a really simple trem, that sounds good, can be made with crap you probably already have lieing around your junk drawer. look no further.
stupid pedal trick to come. ;)
(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/TWOTRANSISTORTREMOLOV2_zps554f002e.png)
Great little layout Jimi, and fantastic looking little trem!
I see how all the wiring matches up to the schem, but I'm confused as to how the mix works :s
Turned all the way one direction, there's no resistance, so Audio out = audio in
Turned all the way the other direction and there's some resistance... so Audio out is a potential divider of mix and the crazy LDR changes?
I guess this is how its working... but I'm still not sure that makes sense in my head...
Quote from: gcme93 on February 20, 2013, 05:08:44 PM
Great little layout Jimi, and fantastic looking little trem!
I see how all the wiring matches up to the schem, but I'm confused as to how the mix works :s
Turned all the way one direction, there's no resistance, so Audio out = audio in
Turned all the way the other direction and there's some resistance... so Audio out is a potential divider of mix and the crazy LDR changes?
I guess this is how its working... but I'm still not sure that makes sense in my head...
hi george,
this thing works GREAT, i used it live last nite, loud, thru a variety of models on my cyberdeluxe. no ticking, and the best part, it acts as a boost.
i don't know if my label for the pots are too good...
the rate and mix controls work as expected, the intensity control varies how bright the led is, and also affects the over all volume of the pedal. it's a really groovy little design!!
the mix basically works exactly as you describe..turned all the way one way, it's input to output. turned the other way, it brings the ldr into play, and the tremolo shorts the output to ground.
it's cool as hell.. try breadboarding it, just a couple parts, and a really nice trem.
the switching works well, too, all you need is a dpdt and you can still have an led....no need for 3pdt!
when the switch is open, the led stays lit. when the switch is closed, it flashes.(i may have that backwards).
i'll try and up a stupid pedal trick in the next day or two.