4011 IC

[twister]

This is the timing section of a inverter that I built. The inverter runs a refrigerator. The delay is to allow the pressure in the fridge to bleed off so the compressor will start. The problem is that the IC gate acts as a amplifier instead of a switch, between 6.2V and 6.5V. This causes the inverter to erratically switch on and off for a second or so. Is there a way to make it switch from low to high with no in between? This is on a solar system.



[MOD edited - cropped and resized image]

 

[HellasTechn]

What voltage and current do you wish to switch on and off ?

 

[twister]

What voltage and current do you wish to switch on and off ?

The inverter requires +5V. The 15K resistor drops the voltage to 5V.

 

[bertus]

Hello,

You can better use an 4093 in stead of the 4011.
The 4093 has a schmitt-trigger inside, that will have a sharp transition.

Bertus

 

[Audioguru]

You need a comparator IC (an LM393 is a dual comparator). It can be adjusted to switch at whatever voltage you want.
you can add "hysteresis" to it so that it switches abruptly and quickly.

You could also use a Cmos logic inverter or gate with a Schmitt Trigger input but you cannot adjust the switching voltage.

 

[AnalogKid]

The CD4093 is a drop-in replacement for the CD4011 and is the right part for this application. The timing will change slightly because the 4093's transition levels are different.

If you want to stay with the 4011, add a 7.5M - 10M resistor from the output of the 2nd one to the inputs of the first one. This small amount of positive feedback will add hysteresis to the circuit, something that is built into the 4093.

Adding reference designators and pin numbers to your drawing will make it much easier to discuss unambiguously.

https://en.wikipedia.org/wiki/Hysteresis#Electronic_circuits

ak

 

[twister]

Hello,

You can better use an 4093 in stead of the 4011.
The 4093 has a schmitt-trigger inside, that will have a sharp transition.

Bertus

Thanks Bertus! This site is a big help; I've learned a lot from it. I will get some of those. Now what to do with a bunch of 4011s?

 

[bertus]

Hello,

The following databook will tell you a lot about the CMOS chips:
https://archive.org/details/RcaCmosI.c.Databook1983
(I have the real book).

Bertus

 

[twister]

The CD4093 is a drop-in replacement for the CD4011 and is the right part for this application. The timing will change slightly because the 4093's transition levels are different.

If you want to stay with the 4011, add a 7.5M - 10M resistor from the output of the 2nd one to the inputs of the first one. This small amount of positive feedback will add hysteresis to the circuit, something that is built into the 4093.

The CD4093 is a drop-in replacement for the CD4011 and is the right part for this application. The timing will change slightly because the 4093's transition levels are different.

If you want to stay with the 4011, add a 7.5M - 10M resistor from the output of the 2nd one to the inputs of the first one. This small amount of positive feedback will add hysteresis to the circuit, something that is built into the 4093.

Adding reference designators and pin numbers to your drawing will make it much easier to discuss unambiguously.

https://en.wikipedia.org/wiki/Hysteresis#Electronic_circuits

ak

Adding reference designators and pin numbers to your drawing will make it much easier to discuss unambiguously.

https://en.wikipedia.org/wiki/Hysteresis#Electronic_circuits

ak

Thanks Anolog

 

[twister]

Thanks AnologKid. I will try the feedback resistor and see if this circuit will work till I can get the 4093.

 

[twister]

You need a comparator IC (an LM393 is a dual comparator). It can be adjusted to switch at whatever voltage you want.
you can add "hysteresis" to it so that it switches abruptly and quickly.

You could also use a Cmos logic inverter or gate with a Schmitt Trigger input but you cannot adjust the switching voltage.

Thanks Audio Guru. I want to stay with a nand gate because I use the other gates. It looks like the 4093 is what I need and I can do everything with one IC.

 

[Audioguru]

The datasheet for a CD4093 shows that with a 5V supply, its input switches at a positive-going input of 2.2V minimum, 2.9V typically and 3.6V maximum. The switching voltage cannot be adjusted.

 

[Bluejets]

Generally accepted practice to control the run of refrigeration via temperature.