MiniPulse Pluse audio options

[dbanner]

Ah. Thanks so much for this.

[Qiaozhi]

I tried to model the cscope circuit with ltspice. I just couldn't get it to oscillate, no matter what I tried.
I began to suspect that the original schematic contained some superficial error. But it is correct. (I traced it from photos of the PCB). The problem is likely that I wasn't modelling it correctly.
I never pursued it any further.
The real question is whether or not the circuit is a true VCO, ie, does it run off of a control voltage. Or does it run off of a pulse train of varying amplitude.
The latter would be inappropriate for cut and paste adaptation to a pI.
The circuit is interesting though, and I'm sure that re-engineering the concept as a basis of a VCO for a pI detector using the 4013 chip is a rational goal.

I tried simulating the circuit in LTspice, and it worked first time.
Simulation attached.

[dbanner]

I tried to model the cscope circuit with ltspice. I just couldn't get it to oscillate, no matter what I tried.
I began to suspect that the original schematic contained some superficial error. But it is correct. (I traced it from photos of the PCB). The problem is likely that I wasn't modelling it correctly.
I never pursued it any further.
The real question is whether or not the circuit is a true VCO, ie, does it run off of a control voltage. Or does it run off of a pulse train of varying amplitude.
The latter would be inappropriate for cut and paste adaptation to a pI.
The circuit is interesting though, and I'm sure that re-engineering the concept as a basis of a VCO for a pI detector using the 4013 chip is a rational goal.

[6666]

I stumbled across a fantastic audio circuit used in the cscope 990b/1220b metal detectors. It uses one dual opamp and a dflop (4013), now only if I can figure out how to adapt it to a pi machine. I'll have to do some analysis on just what's going on with that circuit.

Are you still working on this ?

[dbanner]

I stumbled across a fantastic audio circuit used in the cscope 990b/1220b metal detectors. It uses one dual opamp and a dflop (4013), now only if I can figure out how to adapt it to a pi machine. I'll have to do some analysis on just what's going on with that circuit.

[waltr]

So now for the Audio, Please correct me if I am wrong, The audio out seems to have a hash saw tooth wave form, and what we might want is more of a soft triangle wave form. So what do we need to do to make that happen ? Maybe adding an addon board to PL5 have it go in too a cem3340 or some other VOC chip, or does the change need to happen before or after U10.

An RC will round off the saw tooth if you only wish to have a less harsh sounding output.

If I am looking at the correct schematics it uses a 555 chip to output audio which is then RCR filtered (680R-470n-680R) which will round off the 555's Square wave output.

What does this look like on a scope and what does it sound like to you?

On my HammerHead the audio is a square wave and filtered like the MPP and sound fine to me.
However, I do a VCO (using a PIC 12F1501) to have varying tones (see my HH2 thread for full info).

There are also many other audio circuits in the forum that are nice additions/mods to any of the simpler PI circuits.

[Tibuck19]

Well maybe i was wrong, Perhaps i should put in 3 years of electronic engineering schooling and come back then.

[Tibuck19]

I thought i would start a new post for the Mini Pulse plus Audio alternatives.

Before we start off i would like to quote a posting from Carl Moreland
" Welcome to the new Tech forum

The purpose of this forum is the exchange of ideas relating to the design and operational theories of metal detectors, magnetometers, earth resistivity devices, and any other geophysical instruments that are used in the field of treasure hunting. I hope we can have some interesting discussions and I urge everyone to participate regardless of experience. There is no question too basic for this forum."
Reference posting : http://www.geotech1.com/forums/showthread.php?7033-Welcome!

I do not know how it resonates for each of you, However, my interpretation is you do not need to be a IC chip designer to add to knowledge base, Can we not all agree, we are here for same reasons, We all have a shared passion for metal detectors, and electronics and communicating ideas with others around the world!

Now back to the idea's at hand,

Godigit1,Geoscash1 and a few others are working on a GB Fantastic
Teleno and a few others are working on improving the Preamp Bring the mmp one step closer to a gold detector!
Your all doing a great job! i don't understand half of what you guys are doing, but its great!

So now for the Audio, Please correct me if I am wrong, The audio out seems to have a hash saw tooth wave form, and what we might want is more of a soft triangle wave form. So what do we need to do to make that happen ? Maybe adding an addon board to PL5 have it go in too a cem3340 or some other VOC chip, or does the change need to happen before or after U10.