Programmable timer

I have a simple application where a drive needs to increment the rotation angle of a shaft every .... seconds. The drive itself can be programmed to do the increment when a pulse is being sent to the drive.
The time between two movements is configurable with a signal of 0 to 10 V which equals a time of 10s to 7200 s. When the time is finished i need a small pulse ( 500 ms ). When the timer is being powered on it needs to be resetted and start with a pulse.
Now i'm looking for an timer or another device that i can use to convert the voltage signal to a puls pause time. Any ideas? I've been thinking about use a small Siemens LOGO! but i think there are cheaper solutions out there?

The cheapest solution for something like this is to use a 555 chip and a capacitor. There are a nubmer if 555 cookbooks availalbe.

This is not an off the shelf solution, but it is dirt cheap, probably less than $3.00.

The cheapest solution for something like this is to use a 555 chip and a capacitor. There are a nubmer if 555 cookbooks availalbe.

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How should I connect the external 0-10 V DC to the NE 555? IIRC a NE 555 time base is being derived from an R/C circuit which is being powerd by the supply of the chip?

To make things more clear : the 0-10 V DC comes from a central cabinet in the factory and is being used as a reference for mine and other cabinets.

What a time range, 10 seconds to 2 hours. Is the Voltage -> Time relationship linear? Each volt increase = 719 seconds? How precise must this be?

Building your own bords such as a DAC or ADC is fine for a learning project, but not so swift if your going to place your home brew device in an industrial enviroment.

Your best bet is to small plc with an analog I/O module. I dont know anything about the LOGO, (if it has analog I/O capabilities).

Here's something to look at:

http://web5.automationdirect.com/adc/Shopping/Catalog/PLC_Hardware/DirectLogic_05/PLC_Units

http://web5.automationdirect.com/adc/Shopping/Catalog/PLC_Hardware/DirectLogic_05/Option_Modules/F0-2AD2DA-2

Bernie has a good point. When implementing a timer with the 555 and a cap as a comparator, the v/t relationship is not linear. So its probably not a good solution, just a cheap solution.

You know the rule: cheap, fast, good. You can have any two, but never all three.


Mike, you reminded me of something I once encounterd. A local outfit had a turbine test stand that they couldn't get to work properly. They asked me to come take a look at it. I found a poorly made home grown circuit board in the panel that someone had glued a mouse pad to so that the big globs of solder on the back wouldn't short out against the panel. That wasn't the problem, but when they told me they had paid a consultant $4,000 for that board I was floored. All it was was a hz/v converter. I told them where they could buy one off the shelf. Every once in a great while I encounter a need for a custom board - but that board should still be well constructed.

Alaric said:

Every once in a great while I encounter a need for a custom board - but that board should still be well constructed.

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And DOCUMENTED I would like to add.