I like CD4000 CMOS over BJT TTL because it has a much higher operating voltage range, and it has a very high input impedance, so is easy to interface to other devices or add a signal delay with low values of capacitance.

Hi,

Yeah good point.

I also used to like biasing them into the linear mode and use them for amplification

 

I also used to like biasing them into the linear mode and use them for amplification

The gain goes up as the battery voltage runs down.
Cmos logic was first made by RCA the TV people in the same year 1968 (52 years ago) as the lousy old 741 opamp.

 

The gain goes up as the battery voltage runs down.
Cmos logic was first made by RCA the TV people in the same year 1968 (52 years ago) as the lousy old 741 opamp.

Yeah that's cool maybe we could use one as a crude multiplier.
Does a spice model exhibit that behavior too?

 

RCA made the first CMOS microprocessor, RCA 1802 or COSMAC in 1974.
It was used extensively in the space program, for example, in the Galileo probe to Jupiter in 1989.

 

I also used to like biasing them into the linear mode and use them for amplification

Can you give an example of what you mean by that?

 

Here is how an unbuffered Cmos inverter can be used as an amplifier:

 

I learned logic design with DEC Flip-Chip cards (DTL) in 1966, TTL in 1970. and CMOS from about 1982 on.

 

Can you give an example of what you mean by that?

Here is a relaxation oscillator



Vcc = 5V with a threshold at Vcc/2 and hysteresis

 

Can you give an example of what you mean by that?

See post #42 or #46 where ag graciously supplied the schematic and info.
The main idea is you start with an inverter 'gate' then connect a resistor from output to input that biases it. You then have various options because now you have a somewhat linear amplifier to work with similar to an op amp with no non inverting input terminal.

 

Can you give an example of what you mean by that?

This NatSemi app note shows how to use CMOS inverters to convert an LM358 to rail to rail outputs. You can make one shots with any inverting gate.

 

Here is the Cmos logic IC used in the oscillator in post#48:

 

On channel A is 4069 relaxation astable multivibrator with square output.
On channel B is 4069 driven by a GW instek gag 810.
In getting reasonably close to the FG specs what would the scope show to indicate that the cd4000 series component is producing a good quality square wave.

 

See post #42 or #46 where ag graciously supplied the schematic and info.
The main idea is you start with an inverter 'gate' then connect a resistor from output to input that biases it. You then have various options because now you have a somewhat linear amplifier to work with similar to an op amp with no non inverting input terminal.

Thanks, I didn't realise Audio Guru was talking about the same thing. So the application of this would be when you have a spare gate and you need a 'good enough' opamp? This is a cool trick.

 

Thanks, I didn't realise Audio Guru was talking about the same thing. So the application of this would be when you have a spare gate and you need a 'good enough' opamp? This is a cool trick.

You can make the relaxation oscillator work pretty well for a "periodic" time interrupt. Also, although the original Schmitt Trigger cane in a package of 6 inverters, you can probably get a single part in a SOT23-5 package. Here for example:

http://www.farnell.com/datasheets/1...MIgJK8yqWl6QIVweDICh0NiA3OEAQYBSABEgJSVvD_BwE

Check out this page for making a Schmitt Trigger from a CD4007

https://wiki.analog.com/university/courses/electronics/electronics-lab-28

 

I have never measured the distortion of the Cmos inverter used as an amplifier but I suspect it produces A LOT of distortion.
Here is some info about it:

 

They make great limiting amplifiers when a few are cascaded and capacitively coupled.

 

They make great limiting amplifiers when a few are cascaded and capacitively coupled.
View attachment 206708

Hi,

That looks interesting but would you happen to have a larger schematic that one is a little hard to read?

 

I found the original image of the doorbell receiver:

 

Thanks also I see my brass tuning slug explaining it's diamagnetic properties.
something I had shared with friends in fine tuning wide band coils they decided to re-purposed for their own ego. Shows that things published in forums are open game for hacks. https://www.eeweb.com/extreme-circuits/circuit-project-wireless-doorbell
academia encourages classmates collaborate then the special friendship in china causes an anything goes like Hauwei

 

Its off topic, but
CMOS gates make great fun projects
https://www.onsemi.com/pub/Collateral/AND9983-D.PDF
https://www.hindawi.com/journals/isrn/2013/987179/
http://www.sdiy.org/philgallo/hfvco/AN-0088.pdf