Let's make a Voltage Controlled Oscillator (VCO) 

Its not 33K either - more like 18 ohms!

Glad it helped

I was wondering the same thing - how to hook it up to a speaker

​@@RickNuthman You can take the signal from pin 3 (the one he's showing on the oscilloscope) and feed it into an audio amplifier. Best to do this via another potentiometer, so you can vary the voltage going into the amplifier (start at 0 and turn it up until you hear something). Please note though that the schematic in the video is wrong (as others have commented here as well). As far as I can tell at least: 33k resistor should connect pin 6 and 3 (instead of 6 and 2), and pin 2 connects to ground only via the capacitor, not directly.

@@RickNuthman just plug + into the output and put - to ground If its a small speaker should work :P Pull one out of an alarm clock or something :P This is the simple way lol

Thanks

Cap between pin 2 and ground

Carl is right..actually it was a slight mistake. 2 will go to gnd via the cap..not directly

If you had a penny for everytime you used one of these, you'd have to buy more with the pennies!! LOL!!

Thank you

Cap between pin 2 and ground

Yes, THIS.

?

Rocco Rid Like you, I want more VCO videos

Yes!

MAY I SUGGEST VIDEO PRESENTATION ON PLL.

First of all, the waveform is changed in shape, because the scope is AC coupled and the fundamental frequency of the oscillation is so low, that the DC block cap in the scope has plenty of time to charge and discharge, that is why you see the steady voltage of square wave as an exponentially decayed voltage in the scope (First order RC circuit). For your second question, generally yes, but there will be no negative voltage across the timing capacitor in this circuit, so you can also use polar caps like electrolytic capacitors without any issue. The waveform that you saw on the scope screen is the output waveform (square wave) which is different from the timing capacitor waveform (exponentially charge and discharge). Moreover, negative voltage on the scope screen appears because the input is AC coupled so it removes the dc component of the oscillating wave on the screen. Changing the timing capacitor affects the charge and discharge time, which consecutively alters the frequency of oscillation. So does the resistor. As you increase resistor or capacitor value, the charge and discharge time increases, thus reducing the frequency.

The voltage dependency of this VCO is highly nonlinear (~1/V), so it is not very useful for audio synth.

I have been trying to build an envelope generator.

learnelectronics sounds good. And I understand about getting to projects. Caring for health should come first, imho. 🙂

Main switch mode power supplies, as you mentioned, first generally rectify the main's sine wave to make it high voltage dc, and then using a (discrete or integrated) switch and a transformer, they produce the desired voltage (or current) at the output. In order to turn on and off a switch (for example a power MOSFET) you don't have to apply high voltage to control pin of the switch. Power MOSFETs in SMPSs typically need 10 to 15 volts at the gate. Although the control circuitry of a SMPS is not as simple as an oscillator, generally speaking, you can use 555 timer as PWM source for you SMPS.

Ill see what I can do.

​@@learnelectronics First of all I love your channel, great stuff. Here is my thoughts on figuring out addressable Leds. They say each Leds in a strip is turned on by different frequency. I have considered ideas like how a ir remote control works to spectrum frequency device. Its can also works like a vumeter in dot mode, where the chip on each Led converts frequency back to a set voltage to active the Leds. I think this is intriguing concept and would love to see just 3 leds perform this unknown trick using the 555 timer. I love analog and figuring how stuff works, Thanks

Clearly, he's not an Engineer.

You will need an amplifier. Typically, audio in signals have a max amplitude of 100mV, so you have to reduce the voltage on the output, for instance using a voltage divider.

I will do that.

I know you're supposed to always leave them wanting more but this just seemed abbreviated to me. As if it is incomplete.

Theres a million videos on YT for that

Me too. Given the formulae it's not hard to sort out, provided you know the annotation and method, but what stumps me is having to keep values in my head as I slowly trudge through it. What you have just seen was just like Ohm's law, but with additional levels per value. I call it "ohm's law coleslaw" - it's dead simple to work it out (I'm lying to myself here) provided you can fill each value and keep track.

For early beginning work no. But calculus is the math of change over time. That becomes important as you get into calculating capacitors, amplifiers, etc... also we build integrating circuits

makes me money

Seven is nekkid

Seven of Nine!

Replace the potentiometer by a regulated power supply where +v to pin5 and -v to ground...the basic idea of pot is to vary the voltage instead of using a variable voltage supply

XD been 6 months...hope that doesn't bother u that the reply is after 6 months

Soon, young Jedi, very soon...

Do it while consuming adult beverages, so that you can...Drink and Derive...

Might need to wait a while.. s in F(s) of a Laplace transform is definitely not ”seconds”