Analysis and Test Results of Resonant Scanning Circuit K22

Earl

Analysis and Test Results of Resonant Scanning Circuit K22
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Finished testing the Resonant Scanning Circuit K22 today.  I had it built a few days ago and put it aside as I had started working on testing the Phase Lock Circuit K21.  I ran into a couple issues with K21 in trying to get it to work.  I thought I could at least test the voltage dividers circuit in K21 as it looked very similar in function to one in the Frequency Generator Circuit K2, but I could not get a signal out the CD4006B on pin 4. Turns out the Voltage Controlled Oscillator (VCO) that provides the signal to the voltage dividers requires Signal (F) to be present.  Signal (F) is generated in this circuit so I decided to test it one before continuing with K21. This will give me a signal (F) I know and understand.  I also may have burned out a couple of chips on K21 and needed to step away from it for a little while.  However, I did do enough testing and research to get a better understand of the VCO function and that signal (F) needs to provide voltage levels to the pin 9 of the CD4046B for it to generate the output frequency on pin 4.

I did find in analyzing and testing K22 is that it does not actually do the scanning that is done by K21.  What it does do is generate that the voltage control signal that the VCO needs to generate the scanning frequencies. The CD4046B does all the tests to determine when systems is in resonant then sets the Lock signal (L) high to turn off the scanning control pulse being sent to output (F).  The Lock pulse when high also routes the resonant frequency on input (E) back out on signal (F) which stops the scanning process until system drops out lock, then cycle repeats.

I have written the analysis and test report but need to read and edit it a couple times, I have a lot of errors in first drafts. Will post it here in a couple of days at most but wanted to a least get a screen shot of the normal scanning pulse on (F) posted here.  A31, 555 Timer, generates 12-volt clock pulses, with a wide pulse separation. This means bias resistors and capacitor set the frequency of scans. This pulse train is past to A32 which turns the pulses into a 10-volt double ramp voltage pulse (ramps on both leading and training edges) with a sight pause in middle of pulse. The slope of the ramps control how fast the operational frequency is scanned.  Slope is set by the feedback capacitor on A32.  The result is the voltage control pulse that the VCO uses to generate the operational frequencies that are used to scan for resonance. It should be noted that the control pulses does determine the range of frequencies being scanned that is done in the CD4046B by the bias resistors and capacitors on its inputs. However, in the manual mode of operation output (F) can be used to help set those values.

Bottom line I believe K22 does what it is designed to do.  It provides one of the external functions mentioned in the data sheet for the CD4046B that supplement its ability to lock on a resonant frequency.  The VCO is just one part of that processes and K22 is a key part of configuring it to operate as desired.

I am getting closer to seeing the combined gated pulse and carrier frequency signals. Thought I found it in NOR on Input to K21.  Turned out to just be Inhibit level to CD4046B.  Looks like it is the (G) signal K21 outputs but I am not there yet though I have started testing that circuit.  Completing this circuit and testing it was another step in reaching that goal as I have another input identified and tested.

I also have the Pulser Indicator Circuit K14 built just need the 918m chip which I found on ebay and on the way (surface mount version) but I am not sure how I am going to test that one.

Report now added.
Re: Analysis and Test Results of Resonant Scanning Circuit K22
« Reply #1,  »
Updated Report to correct type on 10 volt voltage regulator in is LM713 also replaced picture with one of final circuit you can see LM713 in back of red board.  I thought I had a problem as final output did not look the same.  Spent couple of hours checking and found the 4016 need a ground on the Latch input.  I had put one on when I was test breadboard version put left it out in this version as it is not part of the circuit.  Made a note of this in test report as well.  I left this ground (green wire sticking Latch connection to remind we I need to make sure K21 (L) interface is working.

That gives me 6 of the 8 boards built and tested.  I can now use this board to aid in testing K21.

securesupplies

Re: Analysis and Test Results of Resonant Scanning Circuit K22
« Reply #2,  »
nice I like the little  mounting you make with label cool

Earl

Re: Analysis and Test Results of Resonant Scanning Circuit K22
« Reply #3,  »
That was the easy part - just a strip of metal cut of with hacksaw and drill holes with drill press.  Need something to mount POTs and switched to.