Fox and Hound cable tracer.

[wendelspanswick]

Hi, I found this circuit for a Fox and Hound cable tracer that used a 4001 as an audio generator for the Fox part of the circuit but when I simulated it in both Multisim and Livewire I couldn't get an output on the oscilliscope.
I used a 0.1uf capacitor for u1 and a 0.47uf capacitor for u47 but couldn't get the top right hand gate of the 4001 to oscillate. Anyone care to suggest why it wouldn't simulate?
Instead I have used two 555 timers for the oscillation and that works on the sim.
Here's the link to the original circuit. **broken link removed**

 

[wendelspanswick]

This is my first post, I was hoping someone could cast an eye over the 4001 circuit to see if it looks like it should work before I go ahead and assemble it. I know it didn't work when I simulated it in Multisim, how accurate are the simulator programs?
Anyone?

 

[Mikebits]

For one thing, those resistors on the base seem huge, 1k sounds more like it. Maybe a typo?

I was looking at the second schematic, first one has 1k.

 

[Roff]

This is my first post, I was hoping someone could cast an eye over the 4001 circuit to see if it looks like it should work before I go ahead and assemble it. I know it didn't work when I simulated it in Multisim, how accurate are the simulator programs?
Anyone?

I got it to simulate with some changes, but there is no guarantee that the cross-coupled multivibrator will always oscillate, and the other oscillator isn't the best either. See Fairchild AN-118.
If I were building this, I would do it as below. It's much simpler, and is guaranteed to run. I simulated it. You might want to tweak the resistor and/or capacitor values to get the sound you want.

 

[wendelspanswick]

Thanks for that guys, I think I will breadboard up the circuits and see which one performs the best before I make a PCB.
Thanks again.
John