MiniPulse Pluse audio options

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" A 555 VCO circuit with logarithmic characteristics"

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This one looks interesting, I think I've seen this circuit adapted for a surf PI project. Would be interesting to see what the frequency vs voltage plot looks like.

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I came across this VCO circuit with an ltpsice simulation to play with.

[6666]

I found this modified vco, works inversely
http://www.next.gr/oscillators/volta...co-l13874.html

[6666]

Would a simple 4046 work for you

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What would be the preferred way to connect an audio chopper to a PI output, a JFET or an ordinary bipolar transistor?

I'm going to try the VCO circuit in the above posts.

I plan to take the input from after the sampling integrator and connect the output via a JFET transistor after the second integrator. I will condemn the 555 VCO section and just add an audio amplifier stage to drive a speaker or headphones.

I'm not sure about the voltages though.

Any help or advice please.

[Polymer]

Now that I am in quarantine, I have been feeling motivated once again to re-engage in hobby building and tinkering.
Only one big problem..... I AM RUNNING OUT OF SOLDER!!!!

All local non-essential businesses are shut down. Supermarket does not sell solder.
Rrrrrr.....

Same here, I'm running out of solder too. My last buy of rolls abroad was round 5 years ago.
In the meantime getting leaded solder is very difficult in the EU as I have found out, only if you have a justified business for that.

I call RoHs faux environmental reasoning.

I really like the Kester 44 (63/37 or 60/40), which oddly enough is not so common in the EU.

A lot of other name brands here have fluxes which I am not fond of.

Good luck with finding good solder or getting it shipped to the island!

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I will run your simulation and give it a try as you have explained, I always see such graphs (Freq. vs Voltage plots) with respect to VCO circuits. Nice to know how to actually execute such a task in LTspice.

Thanks Qiaozhi.

[waltr]

Thanks Q,
Good stuff.

[Qiaozhi]

I did try to add a second .measure command: ".meas tran freq param 1/period" to automatically do this last calculation, which displays correctly in the log file, but results in a blank plot window. Don't know what's going on there.

OK - I've figured it out.
You need to right click in the [blank] plot window and select View>Visible Traces. Then it lists both period and freq.
All you need to do is add ".meas tran freq param 1/period" into the simulation.

Simple when you know how.

[Qiaozhi]

I suspect what you're really trying to do is to generate a plot of frequency versus control voltage.
To do that you need to use the .measure facility in LTspice. Please see attachments.

According to the information I have on the CS-1220, you need to adjust the trimmer R71 (47k) in the schematic [R6 in the simulation] so that the audio frequency is 1060Hz when there's 700mV at the control voltage input. By a matter of trial and error, I found that setting R6 to 14k06 gives an audio frequency of 1060.91Hz, which is close enough.
This trimmer is obviously setting the maximum audio frequency. Then I set up a parametric sweep of the control voltage from 10mV to 700mV in steps of 10mV.
The .measure command determines the time at which the audio output voltage first crosses 500mV after a delay of 30ms, and also where it crosses 500mV the third time. The difference will be the period of the audio signal.

To plot the period versus vc, run the simulation (70 runs), and enter <CTRL> L. This displays the log file with the measured results. Click the right-hand mouse button in the log window and select "Plot .step'ed .meas data". This will display a plot of the period versus control voltage. To display the frequency versus vc, right click on the waveform name (period) and change the expression to 1/period.

I did try to add a second .measure command: ".meas tran freq param 1/period" to automatically do this last calculation, which displays correctly in the log file, but results in a blank plot window. Don't know what's going on there.

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Add another Voltage Source and connect to VIN & ground.Mouse over and right click and then ADVANCED to set parameters.
Select PULSE. Set to RISE TIME to the period and Fall time very short to produce a Ramping Voltage (saw tooth).
A Triangle is done the same way except rise and fall times are the same and half the period.

Thanks waltr, I'm going to have a play with the Pulse parameters in the ADVANCED Vsource settings. Should be very easy to set up.
Will post a screenshot of the results. I may tinker with the values of the circuit to see if I can get a fairly linear response, or at least to get a feel for what the limits of the circuit are.

[waltr]

I ran your simulation. It works very well.

I noted that the control voltage (VIN) must be positive only.

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I'm not sure what voltage is present at the minipulse output. Maybe with a little tinkering this circuit might be adapted to work as a nice little VCO ad-on. If any diy pulse detector can be made to sound like the Cscope 1220B, that's got to be a good thing.

How would I go about plotting the voltage to frequency response of this circuit in LTspice, does anyone know? What parameters for VIN should I use? Should I define the voltage source using PWL?

I guess I'd be aiming for a triangle shape waveform for the control voltage with linear rise and fall.

Add another Voltage Source and connect to VIN & ground.Mouse over and right click and then ADVANCED to set parameters.
Select PULSE. Set to RISE TIME to the period and Fall time very short to produce a Ramping Voltage (saw tooth).
A Triangle is done the same way except rise and fall times are the same and half the period.

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

I ran your simulation. It works very well.

I noted that the control voltage (VIN) must be positive only.

.
I'm not sure what voltage is present at the minipulse output. Maybe with a little tinkering this circuit might be adapted to work as a nice little VCO ad-on. If any diy pulse detector can be made to sound like the Cscope 1220B, that's got to be a good thing.

How would I go about plotting the voltage to frequency response of this circuit in LTspice, does anyone know? What parameters for VIN should I use? Should I define the voltage source using PWL?

I guess I'd be aiming for a triangle shape waveform for the control voltage with linear rise and fall.

[dbanner]

Now that I am in quarantine, I have been feeling motivated once again to re-engage in hobby building and tinkering.
Only one big problem..... I AM RUNNING OUT OF SOLDER!!!!

All local non-essential businesses are shut down. Supermarket does not sell solder.
Rrrrrr.....