Hi All,
Building tractor beam and bit confused of what zener to use as it just says zener?
Any ideas?
it's a 4.3 V zener diode. Go to page 8 of the build doc for some infos.
Sorry I think I've not explained correctly, it's on the switching board marked D2 and just says zener and says refer to chart?
What chart?
The chart is in the doc specifically for the switching board. Different VFE projects use different value Zener diodes on the switching board. In the case of the Tractor Beam, it's a 16v Zener. The chart is on page 7 of the Switching Board build doc. In reality, you could use a 12v, or 18v or none at all. It's only to prevent over-voltage getting to the circuit but if you are careful about always plugging in 9v then it's no big deal on the Tractor Beam.
That would be the Zener chart on page 7 of the switching board BOM (see http://www.madbeanpedals.com/projects/VFE/VFE_SwitchingBoard_v2.pdf (http://www.madbeanpedals.com/projects/VFE/VFE_SwitchingBoard_v2.pdf)). It calls for a 16V zener at D2 on the switching board if you're building a Tractor Beam (i.e, a 1N4745A like this one in the MB cart for the v2 switching board: https://www.mouser.ca/ProductDetail/512-1N4745A (https://www.mouser.ca/ProductDetail/512-1N4745A)).
Ah perfect thank you, I didn't find that very clear.
Will give it another look.
I'm still gathering parts for this build along with a green bean and a death claw.
Totally revamping all my pedals, I've built an mxr flanger, tremolo, phase 90, big muff and a Snow White env filter.
Might also build the coral reef as I like the chorus on the whammy pedal but would like to try a different version.
Completed parts yesterday but unfortunately had IC wrong way round so fried it!!!
Ordered a new one, voltages look good, switch pcb all works fine, can hear that control and switches work but no signal when in bypass?
seems i'm prone to problems on every build!!! i do tend to learn quite a bit though, which im totally happy about.
anyway my build hasnt gone well, in bypass im not getting signal through pedal first of all
effect on sounds distorted, with mix control to left hardly any signal but distorted, mix control to right is just a total mess but can hear guitar signal but no effect.
here are voltages
OPA2134
1- 4.2mv
2- 4.2mv
3- 0v
4- -7.21v
5- 0v
6- 0v
7- varies
8- 8.04v
LM358
1- varies
2- varies
3- varies
4- -7.50v
5- varies
6- varies
7- varies
8- 8.05v
TLE2074
1- varies
2- 4.1mv
3- varies
4- 8.06v
5- varies
6- 4.2mv
7- varies
8- varies
9- varies
10- varies
11- -7.49v
12- varies
13- varies
14- -6.29v
2N5952
G- varies
S- 0.2mv
D- varies
any help would be fantastic as i really love this pedal!!!!!
Anyone have any ideas of how I can get this puppy working please?
I have used wires to connect the jack sockets from J1 and alt for input and J2 and alt for output?
Is this ok or do I need to connect it differently?
I need a new switching board pcb!!!, i've had a tough time fault finding this pedal but i put in the relay the wrong way round then tried taking it out!!
needless to say the pcb hasn't survived!!
I have managed to take everything off the pcb now and i think the parts are ok.
How do i go about ordering a new switching board pcb?
regards
Spence.
Right I have the new switching boards and I've installed and it does switch but cuts the signal out!?
If I leave the effect on and then disconnect the power lead I then see the normal sign, if I have the effect off and then disconnect power it cuts the signal?
Waveform is all over the show when effect is engaged but need to get switching pcb working correctly first so any help is much appreciated.
Regards
Spence.
Let's have a clear pic of the build please.
here's a few pictures, any help is much appreciated.
back with pots
switching pcb front
switching pcb back
right, ive just seen my mistake for the switching pcb, i had wired the screen to the output terminal!!
swapped and get signal now with effect off and see effect on signal.
Next step is getting the effected signal working!! it doesnt look good, will report back with some voltages and try and trace signal to see where it gets to.
I have ordered a C1meg pot which is reverse taper as the one I had broke!
The 3 way switch when in the middle I don't see any signal when mix fully CW.
When 3 way switch to left and right I get very messy waveform.
Speed pot does function asi can see the waveform change, feedback does seem to change waveform along with other pot does seem to do something.
Trim pots work, just need to check voltages on ic's to see if one has malfunctioned.
ok here some voltages:
switching pcb seems to be working fine now and was all along, i had just got mixed up with screen and signal!!
TLE2074
1 - 7.61* this is only meant to be 4mv so problem here!!
2 - 1.1mv
3 - 0.2mv
4 - 8.63v
5 - 0.3mv
6- -1.2mv
7 - 7.61v
8 - varies
9 - varies
10 - varies
11 - -8.22v
12 - 0.1mv
13 - varies
14 - -7.22v
2N5954 (x4)
D - 0.3mv
G - -3v (with some twiddling of bias trimmer i can get gate volatge down to -0.4v but not 4mv
S - 0.3mv
OPA2134
1 - -1.4mv
2 - -1.2mv
3 - 0.2mv
4 - -8.2v
5 - 0v
6 - 0.9mv
7 - varies
8 - 8.64v
V+ is 8.5v
V- is -7.72v
all help is appreciated
this is the waveform with 3 way switch at 2, i dont see any major movement in waveform apart from some little bits, i thought the waveform should pulsate?
this is with the 3 way switch at 3, as you can see the waveform looks all over the show!!!
this is with the switch at 4, chaos!!!
Could anyone help please with this?
It looks like pins 1&14 of the TLE2074 are causing some issue for you. Do you have another you could sub in there? I know I have had issues with those chips in other builds where popping another in solved the wrong voltages. I could be wrong, but you might be able to see if it is the chip by putting another quad op-amp in there (like TL074).
I think I have a TL074 so I'll try that, any other pointers?
I've put in a TL074 and it's slightly better but voltage now 0.625v on pin 1.
Waveform is pulsating a little now so it's better but still not right!!
When switching the phaser to 3 or 4 distorts waveform.
Any other ideas?
I must have been mistaken, and i had just got back from a 12 hour shift!!!
pin1 is 7v on TL074 so still way off, the unit makes a horrible distortion when plugged into an amp!!!!
i've changed the 2N5952 and no difference!!!
where is this 7v coming from!!!???
this pedal is turning into a bit of a headache!!
well looks like i'll just have to give up on this build!!!
OPA2134 voltages on pins 1-3 are wrong and Pin 1 of TL074 goes up and down from about 0.6v to 3v?
was so looking forward to building this phaser but its just done my head in now!!!
looking on pins 1-3 of the TL074 the waveform looks ok, on pins 5-7 waveform looks alright.
On pins 8-10 really fuzzy waveform.
with the effect off i get -6.12v on pin1, when i turn on its varies and jumps around.
attached is a picture of the mix fully CW to show what effect signal i'm getting
If my 22k array wasn't bussed could it cause this problem?
Or if the 10k array not isolated?
I'm going to order the proper 22k as my one was called "commoned" rather than bussed?
Need to find out what the difference is?
Ah I think I understand now, I need a 22k which consists of 3 separate resistors, where as what I have in all the resistors are connected!!
Hopefully this is the only error and I can get this sorted!!
To correct myself I need 2 x 10k isolated resistor arrays which are basically 4 x 10k in each.
The 22k is the bussed or commoned type with a dot at one end so you don't get it the wrong way round.
I've taken out both of what I've put in and have ordered the bourns types.
Pretty sure this was my error and this is what was giving wrong voltage readings.
ok parts arrived this morning, i've managed to change the 10k's and 22k arrays, wired back up with temp transistors which are not matched and i have phasing!!!
Just need to change transistors for matched 4 then change 1M pot for reverse taper then put back in case.
Only problem i have is a high whistling pitch that i need to get rid of?
The high pitch sound is there even when mix is set off CCW?
Any ideas anyone about how to sort this?
as i'm so close to getting this fully working, it sounds pretty good using the TL074, also the TLE2074 works fine as well but the high pitched sound is there all the time when effect is on?
Seems I'm totally on my own here!!!
Will check everything again.
feel pretty isolated here, with no help, both the Deathclaw and this tractor beam i'm having a hard time with and would really appreciate some help please.
This tractor beam i'm getting a high pitched frequency when the effect is off and when the effect is on, apart from that the pedal now works as it should.
could anyone point out which capacitor or what part of the circuit i will need to look at which addresses this high frequency interference please.
I have read that the opa2134 May be missing a cap to tame the top end?
And to try more modern opamp, 4558,5532,tl072 or tl082 to see if high end is attenuated due to these having a high end cap in them?
I maybe clutching at straws here but without any input I don't know.
right i've fixed it, anyone else who gets this issue of high frequency pitch somewhere around 5-8k change the charge pump on the switch pcb.
all sorted.
Hey! Glad you got it working, and sorry there was not much help!
Yeah, charge pumps can be quite capricious sometimes... :)
Yeah, glad you got it working. The nasty part is that there really isn't enough room to mount the charge pump in a socket. Knock on wood but I think I've only had to chase my tail on one pump out of all the builds I've done.
And Boba7, it's a very good day when you can whip out "capricious" in a sentence so smoothly. Well played.
Quote from: gordo on December 10, 2018, 04:11:08 PM.
And Boba7, it's a very good day when you can whip out "capricious" in a sentence so smoothly. Well played.
Haha in french (my language) it's a casual term and I couldnt think of another word :D