not gate oscilator

sss · 24th October 2003, 01:23 PM

hello
i want to make a square wave oscilator using one or two NOT gates , i know theres a way to do it but i forgot how

SY · 24th October 2003, 01:34 PM

You only need one inverter. Run a resistor from output to input. Connect a capacitor from input to ground. Voila! An oscillator!

peranders · 24th October 2003, 01:57 PM

Note that the inverter must have a schmittrigger input!

CMOS40106

If you have two inverters

1 connect those in series.

2 Resistor between input #1 and output #2

3 Cap between input #1 and output #1.

CMOS 4011 or 4001

Very simple and more predictable than the 40106 type because of the uncertain logic levels in the 40106. Philips has much less hysteresis than other brands. It's also temperature sensistive.

I recommend a 4001 or 4011 oscillator. Resistor values between 500 ohms to 10 MOhms! 10-100 kohms is normal I think. Cap values fom 47-100 pF, no upper limit.

sss · 24th October 2003, 06:04 PM

Quote:

Originally posted by SY
You only need one inverter. Run a resistor from output to input. Connect a capacitor from input to ground. Voila! An oscillator!

how to calculate freq?
and what is the duty cycle , do i need schmittrigger input for that circuit?

SY · 24th October 2003, 06:11 PM

Figures you would ask me that, now that I'm 30 km from my notebook

Frequency was something like 4 times 1/RC. I'm sure someone will correct me... Duty cycle was not exactly 50%, but the parts count is low.

sss · 24th October 2003, 06:19 PM

thanx SV
i'll calculate it myself then
hhhhm duty cycle is a problem , i'll need schmittrigger input gate to get 50% right ?

peranders · 24th October 2003, 08:03 PM

Quote:

Originally posted by sss

how to calculate freq?
and what is the duty cycle , do i need schmittrigger input for that circuit?

The duty cucle of a 4001 or 4011 oscillator is very near 50% but if you want exactly 50% you can add a D-flip-flop.

f = 0.23/(R*C) I think, not sure. It's not 1/(2*pi*R*C) but not far from it.

You can use gates with schmittrigger but you don't have to.

Hint: Check the datasheet for CMOS4541 which has an oscillator I'm talking about. BTW: You can in fact use this IC!

24th October 2003, 01:57 PM	#3
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Note that the inverter must have a schmittrigger input! CMOS40106 If you have two inverters 1 connect those in series. 2 Resistor between input #1 and output #2 3 Cap between input #1 and output #1. CMOS 4011 or 4001 Very simple and more predictable than the 40106 type because of the uncertain logic levels in the 40106. Philips has much less hysteresis than other brands. It's also temperature sensistive. I recommend a 4001 or 4011 oscillator. Resistor values between 500 ohms to 10 MOhms! 10-100 kohms is normal I think. Cap values fom 47-100 pF, no upper limit. __________________ /Per-Anders (my first name) or P-A as my friends call me Tube Buffered Gainclone in work \|Thread

24th October 2003, 06:11 PM	#5
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	Figures you would ask me that, now that I'm 30 km from my notebook Frequency was something like 4 times 1/RC. I'm sure someone will correct me... Duty cycle was not exactly 50%, but the parts count is low. __________________ If there's a sucker born every minute, where do the rest of them come from?

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24th October 2003, 01:23 PM	#1
sss diyAudio Member Join Date: Jul 2003 Location: Israel , haifa	not gate oscilator hello i want to make a square wave oscilator using one or two NOT gates , i know theres a way to do it but i forgot how

24th October 2003, 01:34 PM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	You only need one inverter. Run a resistor from output to input. Connect a capacitor from input to ground. Voila! An oscillator! __________________ If there's a sucker born every minute, where do the rest of them come from?

24th October 2003, 06:19 PM	#6
sss diyAudio Member Join Date: Jul 2003 Location: Israel , haifa	thanx SV i'll calculate it myself then hhhhm duty cycle is a problem , i'll need schmittrigger input gate to get 50% right ?