frequency shifter

[dingebre]

Last update I hope.

I've uploaded one last version. I got rid of the Mic/Line jack and am just using an auxiliary in and an "Audio" in. The only difference is the Aux in is normaled to the feedback (per JH's connection diagram). The "Audio in" bypasses the mic pre-amp and is a simple unbalanced input (similar to what Dave Brown did I think).

I also relabeled and reorganized the knobs to make more sense, I hope. Instead of up/down, or on/off, I used sum or diff as this was what the switches are connected to.

I've sent this one off to Schaffer for building.

Again, I used Bulgarian for the name, JH Frequency Shifter, and JH-FS-1

Thanks JH for some truly amazing projects.

David

---

FS-1.jpg
Description:
Filesize:	109.13 KB
Viewed:	481 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

---

---

Blacet JH Shifter rev 2 no mic.fpd
Description:		Download (listen)
Filename:	Blacet JH Shifter rev 2 no mic.fpd
Filesize:	2.27 KB
Downloaded:	475 Time(s)

---

[xpmtl]

[lexvortex]

Hi,

I'm about half way through wiring my freq shifter up and have a few questions:

1. For the APFout, 1inv, INVout, and *cmp_out, where would I connect them to ground? is it necessary to connect them to ground?
2. What is the difference between the Freq LED and the DIR LED, I would think they are similar but would like some clarification.

Thanks for the help
Dave

[jhaible]

[lexvortex]

Hi JH,

Thanks for the help I just finished wiring it up (wow , this has to be one of the most challenging projects yet!!), now to try and calibrate it and see if I managed to get it right

Cheers,
Dave

[lexvortex]

Hi JH,

I finally fired up my Fsa1 to try and calibrate it and right away there were problems

I hooked up the oscilloscope as shown in the diagram and turned on the power and I got one tri wave on probe 1 and probe 2 was flat lined. I turned it off and checked all the wiring and took each board out and checked for correct parts placements and correct IC's and diode's pointing the right way etc.

When I turn the manual knob the freq doesn't change, when it passes through zero the tri wave jumps a bit. The freq LED initially is unlit then goes on and stay on. None of the ICs get hot either.

I tried passing audio through the input and aux input and I get the same signal on both outputs. The input knobs (main in and aux) change the volume, and turning the pot to full mix makes the signal disappear.

Where should I start looking for problems, theres a lot to search through on this board, maybe voltages to certain IC's? I'm kinda lost as to where to start with project, I've built a lot of other projects and got them all working so I know with a little patience and some help I'll get this going too.

Is there anything specific that I can tell you that would help you help me?

Any help would be greatly appreciated
Thank you,
Dave

[jhaible]

[lexvortex]

Hi JH,

Thanks for the quick reply I checked all the voltages at ICs and they are all +-15V and the THAT1510 IC was +-14V. I didn't see which pin to test for a V+ for the LM1496N IC from the data sheet.

Tracing the signal along the VCO structure:(U9, pin 7 is listed twice)
U8, pin 7: triangle. (You have that.)----yes was a triangle
U9, pin 7: triangle - yes or no?-----yes is a triangle (U9 pin7)
U9, pin 7: square wave - yes or no?-----is the same pin as above a triangle(U9 pin 7)
U8, pin 1 : triangle (this is flat - right?) -----yes is still flat line

What should I check for next? I tried replacing C7, but that did nothing.

Thanks again,
Dave

[jhaible]

[lexvortex]

Hi JH,

Yes I get a square wave at U9 pin 1.

Thanks,
Dave

[jhaible]

[lexvortex]

Hi JH,

I was checking everything around the U7a IC and I found my first error in the build, somehow I put 30.6K resistors in for every 30K spot! So now I'm gonna switch them all out and see where that leads me I hope this may fix something

[jhaible]

[lexvortex]

Hi JH,

I double checked each resistor "whew", and they all are the correct value. Should I try replacing the LM13700N (U7)? I don't want to blow another one if the problem lies elsewhere but maybe it's safe to try?

I'm still not sure about the resistors R29-30, should I be seeing +-3.5V?

Thanks again,
Dave

[jhaible]

[lexvortex]

Hi JH,

I replaced all the 30.6K with 30K resistors (I had already removed them by the time I got your message) and I tried replacing U7, (first testing for the short to ground). I still have no triangle wave at probe two (R37).

I measured R29 and R30 by placing two the leads from the voltmeter one on each side of the resistor, at R29 the was no voltage across the resistor and at R30 the voltage was a constant -12.85V or 12.85 depending on which lead was on the resistor leg, and the voltage was not affected by turning the manual knob.

What should I look for next? could one of the transistors be broken?

Thanks again for all the help so far ,
Dave

[jhaible]

[lexvortex]

Hi JH,

[jhaible]

[lexvortex]

Hi JH,

Great I've got a triangle wave at R38!!!. This is the second time I've been a victim of mixed up pin outs! From now on I guess I have to check all my transistors
Now to calibrate it

Thanks again for all the helpv
Dave

[lexvortex]

Hi JH,

Sorry to bother you again It seems that my triangle waves are not 90 degees our of phase, they are perfectly in phase. Does that mean I did something wrong in with my capacitor/resistor calculations?

Thanks again,
Dave

[jhaible]

[lexvortex]

Hi JH,

[jhaible]

[lexvortex]

Hi JH,