CSS555C alternative, to create a long delay

Thread Starter

cgw94

Joined Jun 11, 2020
41
Was looking for a way to create a long delay, essentially I want to activate a circuit for a certain amount of time once or twice a day. I really dont have the space or budget to add a micro controller. I found some old articles talking about the CSS555C but it seems hard to find now. Is there a better solution on the market?


I also can't have it involve a giant RC circuit so I was hoping there was another chip out there. A little programming isnt a bad thing just want it to be as simple as possible.
 
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Audioguru again

Joined Oct 21, 2019
2,088
The CSS555 is a Cmos 555. I do not know why a standard readily available Cmos 555 cannot be used for your project like an ICM7555, LMC555 or TLC555. With a 20M resistor and a 10uF film capacitor its timeout is almost 200 seconds.
If an electrolytic capacitor is used then its leakage current might cause no timeout.
Cmos oscillator/counter ICs might still be available for a longer timeout.
 

MisterBill2

Joined Jan 23, 2018
7,320
The cmos CD 4060 includes the potion of an RC oscillator and a long divider string. So it can provide much longer delays with a 1 minute or even ten second RC time interal. if 4095 seconds would be long enough. But the output ids only 5 volts so you may need a transistor such as the MPSA13 to provide a higher current capability. So look at the applications of the MC14060 or CD4060 IC.
 

Dodgydave

Joined Jun 22, 2012
9,686
Easiest option is a digital plug in timer, these use a relay which you can modify and use the contacts to switch on your item on .


PL15115-40.jpg
 

AnalogKid

Joined Aug 1, 2013
8,705
AND - CD4521.

Also, Both Linear Tech and Maxim make silicon oscillators, and might have one with a long divider built in.

ak
 

djsfantasi

Joined Apr 11, 2010
6,971
A space limit? An 8-pin microcontroller is no bigger than an 8-pin 555 timer. And about the same cost.
Add a TO92 N channel MOSFET (2N7000) and two resistors, and you can switch just about anything.

If you can program an Arduino, it’s IDE can be used to develop a program for an ATTiny85 (8 pin MCU). And with a Sparkfun programmer ($17), the chip can be programmed from your laptop and the IDE.
 

MisterBill2

Joined Jan 23, 2018
7,320
Here's a circuit using a CD4060 that can time up to 24 hours with a relatively small RC for the oscillator.
YES!!! Thanks for the post! That is what I was talking about, almost exactly. I had not been thinking all the way to the relay and driver transistor.Much smaller and cheaper than an arduino, and it does not need such a complex support system or a regulated power supply. Nor does it need an external computer and compiler to make it run.
The link does take a while to pop up, so a bit of patience is needed.
 

AnalogKid

Joined Aug 1, 2013
8,705
Yes. For $1-ish, an 8-pin PIC can give you a multi-year delay. If you don't need great precision, the internal clock is good for about 1% in some models (working from memory). With a few lines of code you can set up a count-and-compare loop that is incremented by an internal flag that is the CPU clock divided way down. Or use a uC with an internal RTC.

ak
 

upand_at_them

Joined May 15, 2010
552
As AnalogKid said, you can make the delay as long as you want, it's just incrementing a variable. My experience with the 1% accurate PIC's is that they're even better than that. But still, 1% is 14.4 minutes per day. Keep that in mind. Adding a crystal will get you much better accuracy if you need it.
 

djsfantasi

Joined Apr 11, 2010
6,971
Could i get a long delay with just a simple controller chip like that?
You can easily get long delays with an 8 pin MCU. You can also get multiple events based on the clock. Or have multiple inputs... up to five... to control your output. Or up to six outputs based on individual times. With code, the tiny MCU can give you lots of flexibility.
 

MisterBill2

Joined Jan 23, 2018
7,320
With that 8 pin micro you also need a fair amount of extra I/O and if you need to change the time setting you need to get in and revise the software. Also you MUST have a regulated power supply, and lots of esd PROTECTION. Even better, you need to be skilled enough to create the code, compile it, and down-load it. And if the device needs to be replaced just hope that it is still available. The CD4060 is made by several companies and has been around for many years and will still be around for many more.
 

djsfantasi

Joined Apr 11, 2010
6,971
With that 8 pin micro you also need a fair amount of extra I/O and if you need to change the time setting you need to get in and revise the software. Also you MUST have a regulated power supply, and lots of esd PROTECTION. Even better, you need to be skilled enough to create the code, compile it, and down-load it. And if the device needs to be replaced just hope that it is still available. The CD4060 is made by several companies and has been around for many years and will still be around for many more.
Good points. Except the extra IO. What do you mean by that?
 

MisterBill2

Joined Jan 23, 2018
7,320
Good points. Except the extra IO. What do you mean by that?
Extra I/O means thet the 8 pin IC is not able to drive any load beyond a logic IC. So it needs either a higher gain transistor or a buffer IC in order to do anything useful. . And it needs something external to tell it to start. And it probably needs a crystal and 2 capacitors for the clock oscillator.
 

Thread Starter

cgw94

Joined Jun 11, 2020
41
With that 8 pin micro you also need a fair amount of extra I/O and if you need to change the time setting you need to get in and revise the software. Also you MUST have a regulated power supply, and lots of esd PROTECTION. Even better, you need to be skilled enough to create the code, compile it, and down-load it. And if the device needs to be replaced just hope that it is still available. The CD4060 is made by several companies and has been around for many years and will still be around for many more.
Ah right ya forgot to mention the voltage supply is essentially coming from a pH probes voltage im boosting. (with batteries but very unstable)
 
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