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Modification of anti-bark control circuit - help please!
- Thread starter olive
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CDRIVE
Hauling 10' pipe on a Trek Shift3
Oops I missed your post. A Crystal earphone connected to probes would find the uC pin that generates the audible tone. It's been my favorite pocket tester since the 50's.
Chris
KrisBlueNZ
Sadly passed away in 2015
I can't see where the base drive comes from. The track disappears under the ultrasonic transducer and I can't tell where it comes out. But luckily, Chris has suggested the answer - a crystal earpiece. Otherwise you can use a signal tracer.
When you've detected which pin has the audible signal, you won't be able to tell whether that pin only carries the human-audible signal and the ultrasonic signal is on another pin, or whether both frequencies come out on the same pin (which I think is more likely, but not certain).
If you can get access to an oscilloscope, you will be able to tell. Another possibility might be to cut the track from that pin, and see whether the dog can still hear it when you activate it. If the dog can still hear it, there's another pin that generates the ultrasonic frequency, and you've solved your problem. (Cutting the track may not be exactly the right thing to do to disable that tone; it may interfere with the operation of the circuitry that follows. But you could also argue that if it seems to be deterring the dog, and not audible to you, then your work here is done.)
If the dog doesn't get deterred, then cutting that track must have also disabled the ultrasonic tone, which means both tones come out on the same pin. In this case, you'll need trace out the circuit that follows that pin. I'm interested in whether that signal goes through one half of the dual op-amp. (I'm assuming the rear half is the microphone preamp.)
Adding a filter to do what you want may prove to be a lot of work though.
I also suspect that some of the PIC's pins are used as configuration inputs; by changing the states on these pins, you may be able to change the behaviour of the firmware, and you may be able to change the tones it generates. Again you need to trace out the schematic to be sure which pins aren't used for anything else. But that device has twelve I/O-capable pins, and there doesn't seem to be an external crystal, which is about nine or ten more pins that it needs for its basic function of detecting sustained loud sounds and generating an output frequency!
Some notes on the PIC pins:
PIC16F636-I (14-pin DIL SOIC)
1=VDD, 14=VSS
2=RA5/T1CKI/OSC1/CLKIN (GPO-capable)
3=RA4/-T1G/OSC2/CLKOUT (GPO-capable, fixed freq capable)
4=RA3/-MCLR/VPP input-only
5=RC5 (GPO-capable)
6=RC4/COMP2OUT (GPO-capable)
7=RC3 (GPO-capable)
8=RC2 (GPO-capable)
9=RC1/COMP2IN- (GPO-capable)
10=RC0/COMP2IN+ (GPO-capable)
11=RA2/T0CLKI/INT/COMP1OUT (GPO-capable)
12=RA1/COMP1IN-/VREF/ICSPCLK (GPO-capable)
13=RA0/COMP1IN+/ICSPDAT/ULPWU (GPO-capable)
Every pin I've labelled GPO-capable COULD be a frequency output.
When you've detected which pin has the audible signal, you won't be able to tell whether that pin only carries the human-audible signal and the ultrasonic signal is on another pin, or whether both frequencies come out on the same pin (which I think is more likely, but not certain).
If you can get access to an oscilloscope, you will be able to tell. Another possibility might be to cut the track from that pin, and see whether the dog can still hear it when you activate it. If the dog can still hear it, there's another pin that generates the ultrasonic frequency, and you've solved your problem. (Cutting the track may not be exactly the right thing to do to disable that tone; it may interfere with the operation of the circuitry that follows. But you could also argue that if it seems to be deterring the dog, and not audible to you, then your work here is done.)
If the dog doesn't get deterred, then cutting that track must have also disabled the ultrasonic tone, which means both tones come out on the same pin. In this case, you'll need trace out the circuit that follows that pin. I'm interested in whether that signal goes through one half of the dual op-amp. (I'm assuming the rear half is the microphone preamp.)
Adding a filter to do what you want may prove to be a lot of work though.
I also suspect that some of the PIC's pins are used as configuration inputs; by changing the states on these pins, you may be able to change the behaviour of the firmware, and you may be able to change the tones it generates. Again you need to trace out the schematic to be sure which pins aren't used for anything else. But that device has twelve I/O-capable pins, and there doesn't seem to be an external crystal, which is about nine or ten more pins that it needs for its basic function of detecting sustained loud sounds and generating an output frequency!
Some notes on the PIC pins:
PIC16F636-I (14-pin DIL SOIC)
1=VDD, 14=VSS
2=RA5/T1CKI/OSC1/CLKIN (GPO-capable)
3=RA4/-T1G/OSC2/CLKOUT (GPO-capable, fixed freq capable)
4=RA3/-MCLR/VPP input-only
5=RC5 (GPO-capable)
6=RC4/COMP2OUT (GPO-capable)
7=RC3 (GPO-capable)
8=RC2 (GPO-capable)
9=RC1/COMP2IN- (GPO-capable)
10=RC0/COMP2IN+ (GPO-capable)
11=RA2/T0CLKI/INT/COMP1OUT (GPO-capable)
12=RA1/COMP1IN-/VREF/ICSPCLK (GPO-capable)
13=RA0/COMP1IN+/ICSPDAT/ULPWU (GPO-capable)
Every pin I've labelled GPO-capable COULD be a frequency output.
Last edited:
tracing with oscilloscope question
i found an oscilloscope at work that i can use, but i'm guessing that i need the circuit to be producing the ultrasonic and audio signals to be able to trace/detect them with the oscilloscope. other than yelling into the mike, should i be able to trick the circuit into producing a signal? Can you recommend methods?
My best guess is to put a DC voltage at the microphone input, but I don't know what an acceptable voltage would be, so i should hook up a volt meter to the mic and yell into it to see what the max voltage is and use something slightly less than that. does this seem reasonable?
i found an oscilloscope at work that i can use, but i'm guessing that i need the circuit to be producing the ultrasonic and audio signals to be able to trace/detect them with the oscilloscope. other than yelling into the mike, should i be able to trick the circuit into producing a signal? Can you recommend methods?
My best guess is to put a DC voltage at the microphone input, but I don't know what an acceptable voltage would be, so i should hook up a volt meter to the mic and yell into it to see what the max voltage is and use something slightly less than that. does this seem reasonable?
KrisBlueNZ
Sadly passed away in 2015
I don't think putting a DC voltage on the mic preamp is a good idea. Just try yelling into it.
CDRIVE
Hauling 10' pipe on a Trek Shift3
Download Barking Dogs - Jingle Bells and put your laptop, iphone, ipad, whatever near the mic.
Chris
Chris
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