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johans121
Joined: Jun 19, 2007
Posts: 178
Location: Huntsville, AL (USA)
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 Posted: Sun Apr 05, 2009 1:12 am Post subject:
Burst Generator; Internal Clock Problem....
Subject description: Help!! |
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Hello,
Newbie here....
I just got through building the Burst Generator and everything seems to be working fine except for the internal clock. It doesn't seem to be oscillating. I've spent the last 3 hours looking it over & honestly I'm too much of a newbie to even know how to properly troubleshoot this beyond the basics.
-All resistor & capacitor values are correct
-All diodes are oriented correctly (and are the correct type)
-Solder connections have been checked for connectivity between pads
-I am using a 2Meg pot for the internal clock's speed - only two wires soldered, one to the middle lug, and another to a side lug. Both wires are going to the "pot" pads on the PCB
-pin 6 of the 106 seems to stay high all the time
I do have a scope, and I've tested everything out with an external clock and I can see that the main bulk of the circuit is working.
Can someone give me some tips on where to start looking?
Also, can someone please explain to me how the clock works so I can make sense of it for future applicaions?
Thanks,
Jim
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e-grad
Joined: Sep 12, 2008
Posts: 142
Location: Berlin
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| Posted: Sun Apr 05, 2009 2:07 am Post subject:
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Exactly the same or rather similiar prob. here. When I probed the int. clk with a scope I've seen the waveform of the clk. However for some reason it doesn't make it's way to the output.
At the moment my connector to the scope is broken thus I postpoend furhter investiation.
However, I learned from the CGS-Yahoo-group that not any CD40106 is working equally good thus s.o. recommended the Texas Instr. chips.
Other than that an exremely cool module! |
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synthmonger
Joined: Nov 16, 2006
Posts: 578
Location: flada
Audio files: 3
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| Posted: Sun Apr 05, 2009 7:34 am Post subject:
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| I had a similar problem and I solved it by grounded the cap on the oscillator. Tripple check to make sure it's grounded. |
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e-grad
Joined: Sep 12, 2008
Posts: 142
Location: Berlin
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| Posted: Mon Apr 06, 2009 12:35 am Post subject:
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From cgs-Yahoo-group:
| Quote: | The first thing I would so is remove the diode connected to pin 5 of the 40106. That will let the oscillator free run. If you are trying to do any tests with the generator in its "hold" state, the oscillator will not run.
Ken
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johans121
Joined: Jun 19, 2007
Posts: 178
Location: Huntsville, AL (USA)
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| Posted: Mon Apr 06, 2009 2:08 pm Post subject:
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False alarm!!! Sorry.
I was expecting a free running clock. The clock signal is only present at CLK-O when a trigger input is sent to the module....
It works AOK!
Thanks for the help!
-Jim
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-Jim |
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e-grad
Joined: Sep 12, 2008
Posts: 142
Location: Berlin
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| Posted: Mon Apr 06, 2009 4:18 pm Post subject:
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 Not mine! Unless I remove the diode mentioned (see quote above). Strange. |
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johans121
Joined: Jun 19, 2007
Posts: 178
Location: Huntsville, AL (USA)
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| Posted: Tue Apr 07, 2009 10:26 am Post subject:
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| e-grad wrote: | | Not mine! Unless I remove the diode mentioned |
Just to make sure I was clear. My internal clock is not present at CLK-O unless I present a trigger to the module. In otherwords, the clock is NOT free running. I didn't know this when I began testing the module, I thought it was going to be free running, so when I didn't see a clock signal at that pad I assumed something was wrong.
My findings are congruent with Ken's statement.
I have no formal EE background, everything I know about electronics is what I have learned while building synthesizer modules. I didn't know by looking at the schematics that the clock was blocked by the diode and only available when a trigger signal was present to start the process. Now that I have this nugget of information I'll study the schematics again to see if I learn anything new 
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e-grad
Joined: Sep 12, 2008
Posts: 142
Location: Berlin
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| Posted: Wed Apr 08, 2009 3:11 am Post subject:
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| johans121 wrote: | | Just to make sure I was clear. |
You were absolutely clear. However, I couldn't bring out any pulses from both of my BGs unless I attach an ext. clk OR remove the diode.
A trigger must be present at the trig in in both cases. |
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