Grandparents revenge toy

[marcbarker]

I just had to post this:

cat plays with mini theremin

YouTube - cat plays with mini theremin

 

[MrDEB]

That is funny

thanks for posting

 

[MrDEB]

LOST with RC caculations

If adding two more occilators as Audioguru suggested (using the leftover 4069 hex inverters) what componet values suggested.
I can't get a simulation to work to determine the frequency output and forget using any math on this end (I just don't get the hang of math)
I get lost sometimes with ohms law!!
20ma = .020 amps??
I like audiogurs idea

 

[kchriste]

I can't get a simulation to work to determine the frequency output

I wouldn't worry about trying to SIM the exact frequency. There will be variations between different 4069s anyway. Tweak it on a breadboard.

20ma = .020 amps??

Yes!

I like audiogurs idea

It would certainly sound more pleasant. I thought this was supposed to be a revenge circuit, so maybe you should leave the square waves raw and raspy.

 

[MrDEB]

I can't do that to my daughter

besides she just had a new baby boy on Aug 1st.
I just liked the sound of grandparents revenge
your parents am sure told you when you were bad that when you have kids they will be ten times worse ---lol
need to order parts, ordered the low drop out reg from Allied yesterday.They have IMO a good price on 18f1320 PICs. something like $2.68each.
need to place order with Mouser for remainder.
attempting to sim the oscillator section to see what values to order but ??
contemplating adding 25% to one oscillator and subtracting 25% for second oscillator, from original component values.
I did notice that the antenna circuit has same compoent values as oscillator section??
don't know if it will make a difference??

 

[audioguru]

To make a musical chord the frequencies must be about 26% to 33% different.
The frequency trimpots might stretch the frequencies enough. To change the frequencies more then reduce the value of the resistor in series with the frequency trimpot.

The antenna oscillator has the same parts values as the other oscillator so that without your hand near the antenna their frequencies are the same and there is no "beat" note. The beat note is the difference frequency between two frequencies that are added in the diodes mixer circuit. When your hand moves near the antenna it increases the stray capacitance of the antenna oscillator which reduces its frequency and the diodes mix the two oscillator outputs and produce a "beat" note.

OOps. Additional oscillators WILL NOT WORK properly.
They must have their frequency set to the same frequency as the first two oscillators for no sound when your hand is not near the antenna. So the additional oscillators will sound exactly the same as the first two oscillators.

You can try adding an additional oscillator that has its frequency set to produce a tone when your hand is not near the antenna. It will play all the time but its beat note will also change and will be different to the main tone when you hand moves near the antenna.

 

[MrDEB]

I read the circuit description

and yes the reason the two oscillators have the same parts are due to the same explanation you just described.
either your a genius or you read faster than I did--lol
so the two other oscillators are out.
O well!
remember a 4 year old is going to play with this and drive his parents nuts! --lol
I looked at the board layout from the pics and maybe do my layout the same but I am adding an amp.
In the circuit description it mentions that c6 attenuates the inaudible heterodyne products.
????????????????????
should or could add this to my circuit?? using the lm386??

 

[audioguru]

R6 with C6 reduces frequencies above 60Hz which is almost all frequencies.
R4 with C5 reduces frequencies above 727Hz.
Without C6 then simply increase the value of C5 to cut more high frequencies.

 

[MrDEB]

Got email from designer=suggestions

Your suggestion that the lowpass filter be incorporated in the path before the '386 seems okay, but your C5 (10uF) will short any audio signal, so you probably will want to eliminate it. You may have to tweak your R5 for the correct volume range. You may want to incorporate a 2-pole filter, so that any high-frequency artifacts are thoroughly attenuated.
Keep or eliminate C5??
a 2 pole filter??
R5 too large or ??
maybe build a filter using the leftover inverters??
suggestions or thoughts???

 

[MrDEB]

I found this example

have no clue what values to use etc.
original schematic was for a guitar pedal?
R2 was 5M changed to 1 M witl little difference in frequency output but then I may have wrong type of input etc??
someone who knows about filters may have some thoughts??

 

[audioguru]

Your suggestion that the lowpass filter be incorporated in the path before the '386 seems okay, but your C5 (10uF) will short any audio signal

The original C5 was only 0.01uf. Yours is 1000 times too big at 10uF.
It is part of a lowpass filter.

You may have to tweak your R5 for the correct volume range.

You don't have R5 and don't need it.

You may want to incorporate a 2-pole filter, so that any high-frequency artifacts are thoroughly attenuated.

a two-pole filter is not much better than a one-pole filter. Simply reduce the cutoff frequency for the one-pole filter.

R2 was 5M changed to 1 M with little difference in frequency output

Your last circuit uses TTL logic ICs that have a very low input impedance. The original circuit uses Cmos logic ICs that have an extremely high input impedance.

Your circuit with the TTL ICs will not work the same as the Cmos oscillator and is not an oscillator.

 

[MrDEB]

Multisim dosn't have a 4069

used what it has for description purposes=sorry for misinformation mistake.
just go with what I have then??
just contemplating the leftover 4069 sections??

 

[audioguru]

used what it has for description purposes=sorry for misinformation mistake.
just go with what I have then??
just contemplating the leftover 4069 sections??

I mentioned that an additional oscillator can be made but if its frequency is shifted to produce chords then it will play all the time and will not turn off. Try it.

 

[MrDEB]

after I build this for grandson

while in Vancover, washington.
I plan on experimenting with this circuit more.
I have ideas about integrating a PIC into circuit?? using ADC and/or DAC
throw in a VCO and lots of photo transistors instead of an antenna.