inverting amp question

Normally, what you say is true. Unfortunately, in this circuit that is not the case. Look at pin 7 on the 555 timer; it's connected to the junction of R6 and R7, but there is no dot; there should be one. The circuit won't function without a connection there.

[eta]
OK, so I guess this was the page where you originally found the circuit:
http://members.shaw.ca/roma/train.html
It would've helped a great deal if you'd included the page reference in the beginning.
It would also seem to be a case where the original schematic may have been drafted in crayon too. at which point all bets are off
 

Ron H

Joined Apr 14, 2005
7,063
Hopefully I have corrected all the errors caught by others. I noticed that the outputs of the 4017 are shorted together. I added D6-D13 and R11 to eliminate this problem. I also added R12 and C12, as shown in all schematics in the datasheet.
 

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Thread Starter

smoking 555

Joined Sep 21, 2008
25
thanks guys gonna give it a shot. will post the results but just seeing the changes you guys made gives me a good feeling its gonna work. thanks again you guys are top notch!!!
 
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