- I found no hint to the two jumper connectors near pin 1 of U10/12, right beside R59/78. Referring to the schematics of the mainboard, they set the input of the 1496 either to ground or to +vb.
It's been a long time since I wrote down (and performed) that adjustment procedure, but I remember the CV rejection adjustment was performed with a rather brutal signal, to make the adjustment easy. Don't expect the signal to br really zero in that test; just minimize it to get the best out of your LM13600. You can still try a different chip - they vary a lot - but I don't think it's necessary. Test conditions are to exaggerate the effect, fo rcomfortable adjustment, and they don't reflect what's happening in normal operation.
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
I recently finished my modular frequency shifter. A tribute to Jürgen!
I dropped some features to fit the space on the front.
But with many patches I made until now, I didn't lack something.
On the other hand, I modified a little (thanks to Dave @ ModularSynthesis.com and funky40 for some suggestions).
Here's a picture of the front:
What I did:
I dropped
- the gain pot (used a trimmer instead) because of the modular levels
- the out level pots
- the range fine pot
- the possibility to switch 'sum' and 'diff' outs and bypass them
I modified and added:
- a buffered VCO Out and normalized it to the input
- a feedback loop with the aux input hard wired as feedback level
- polarized inputs for both exp and lin modulation, with a center tapped pot for lin mod and a dedicated switch for exp mod.
I dropped the green signal LED also. I tested the shifter with mic sensitivity and noticed a noise / hiss with the signal LED flickering when turned up the mic gain fully.
But maybe this was depending on the the rough wiring.
I found out that carefull wiring is very important for the clearness and defined sound of the shifter, so I wired every audio connection shielded.
My second fs1a I will build into a 19" enclosure for common purposes. I think it will be full-fledged.
@Jürgen:
First, thanks for this fine device.
One question I have:
Is there a special reason why you didn't link the groundplanes on both sides of the second pcb (mic preamp, dome filter etc.)? Instead you designed many solder joints for the groundplanes on the different sides around the pcb.
I bend the legs of a jumper connector and soldered it to one of these joints. See this picture:
So I can set the groundplane of the component side to ground. Until now there are no problems, but I would like to know the reason. Thanks.
Grounding is such a complex issue, depending on so many external factors (what kind of grounding you have in other devices that are connected, on your enclosure, and so on), that I simply provided as much flexibility as possible. Using a jumper is a good choice to test whatever works better in your environment. I guess in most cases you won't see any difference at all.
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
There's a video back on page 19 of this thread that shows those 2 leds in action. Basically the Dir led indicates which way the shift is happening - it's a two color led, and in mine green means it's shifting up, and red is downshifting. The freq led basically pulses along with the freguency of the carrier signal - at no shift it's cycles really slowly, at higher shifts it speeds up.
I used Dave's mods for the output gain and inverting attenuator for the expo FM.
I can't believe it works! My patience (which was severely tested, spending 12 hours making sure everything was right while populating the PCB's) has paid off. I really didn't want to troubleshoot it.
This thing is so fun! Thanks so much Jurgen! (and sduck and Dave for helping me figure things out)
[/i] _________________ " I went through quite a few trannies til I found one I liked" - Wild Zebra
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
Here's a quick vid I made with the FS1A. It was supposed to feature more tweaking of the shifter but my camera batteries died It also features the living VCOs and the Interpolating Scanner acting as a waveshaper.
_________________ " I went through quite a few trannies til I found one I liked" - Wild Zebra
temporarily sold out, but will be available again in the 2nd week of December 2010
Got a lot of orders for these, recently.
I'll put them back in stock withing 2 or 3 weeks.
No need to preorder - just order in the 2nd week of December if interested
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f) Last edited by jhaible on Fri Dec 10, 2010 2:21 am; edited 1 time in total
JH. _________________ "I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
Hello Jürgen.
in my modular i have some attenuators pots, so i decided to omit the 10K log input pot, but the problem is that i can't leave the input aux without a jack plug in, if i don't do that i dsitoy my ears and speakers
I try to solder a 10k resitor between ground and aux in but it's the same problem. For the moment i disconnect the comon of the feedback mode switch.
Would you tell me if there is an other solution to resolve this problem
without add a pot on the front panel because there is no place left.
Thank you.
Have a nice day.
Regards Fred.
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