Did you read more in the datasheet?
The minimum load is 1 mA for regulation.
Hi Mr Crutschow,You could try increasing the value of C1 and/or C4.
If the contact closure time of the clock switch is short than you could just eliminate C1 and R1.
A polarized cap is okay for C1 as long as the (+) terminal goes to the input (connection to C4).
You didn't show the capacitor polarity on the schematic, which you should for any polarized capacitors.
That could be done with a microprocessor but you'd need some way to indicate when the hour hand reaches a particular location (such a 1:00) so that it can be synchronized to the hand.What would it take to make the solenoid strike the hours 1-12 as a normal mechanical clock does?
Mr C, Thanks for the input. The clock motor I am using in the cct. you helped me with has a set of contacts which close briefly every hour on the hour, and this is used to trigger the solenoid with a single pulse. That is working well. I just want to make it more realistic by striking the correct number of blows on the gong.That could be done with a microprocessor but you'd need some way to indicate when the hour hand reaches a particular location (such a 1:00) so that it can be synchronized to the hand.
Any idea on how to do that with the clock you have?
I'm not that familiar with microprocessors, so can't make an informed recommendation for a micro-power device, so hopefully someone with more knowledge can help with that and the program.. What type of microprocessor would be suitable for this, how would it be programed and incorporated into the existing cct. you gave me?
Hi,I'm not that familiar with microprocessors, so can't make an informed recommendation for a micro-power device, so hopefully someone with more knowledge can help with that and the program.
The Micro would replace my circuit, as it can directly generate the required pulses.
Mr Al,Too bad you cant modify the clock itself. Sometimes the mechanisms are very simple. You have to be able to get inside the clock though of course and find out what causes the switch to close and open, then see if you can modify that to provide a shorter closed period. Might still need a relay though to handle the current if the current is higher than the rating of the switch contacts.
Using a microcontroller is fairly simple. Using an Arduino you could have it running in a half hour.
The Arduino library contains an LED blink program you could easily modify to do what you need.
But why not just a simple 555 timer with additional output transistor? That seems simpler.
Hi Mr Al,Oh you mean like one of those annoying coo-coo clocks (ha ha).
I thought you just wanted it to ding once per hour.
So at 1 o'clock you want 1 ding, 2 o'clock 2 dings, etc.
You are right in that a microcontroller is the simplest way to go requiring just one chip and one drive transistor if the dong is a little higher current. Otherwise you have to build up a digital counter using a 4 bit counter along with a clock and gating circuitry...not something you probably want to get into, and would use more power anyway.
My suggestion then is to look into the Arduino line of uC's. If you want to run on batteries you just have to look into ways to put the chip to sleep so that you get long life. Otherwise use Microchips uC's (now part of Atmel too). I use a Microchip uC as a refrigerator monitor and get two years battery run time using just two AA batteryies, and it blinks a high power LED every 10 minutes to indicate the inside temperature.
Anyway, a program to detect the clock pulse along with a software counter would do the trick. You'd have to provide a switch or something too so that you can sync the clock to the uC program say at 1 o'clock.
It would not be much of a program but how hard it would be for you to do would depend on what you have done in the past, like if you have worked with any uC in the past. If you have not done this before it will be a bit of a learning curve, but with Arduino it should be fast although you'd have to look into how to power down for battery applications as they dont provide for that with most of their ready made PC boards.
For example, the Nano board, is small and easy to use with their IDE. But as i said you'd have to look into how to power down and keep the chip in a mode that could still detect the clock pulse.
So this partly depends on how you want to approach this implementation.
Come to think of it though, i am not sure you could power down a CMOS logic circuit too easy so you'd have to look into the power consumption before you think about doing it that way. With the uC chips out there you should be able to do it and get reasonable battery life.
If on the other hand you can keep this thing plugged into the wall outlet, that would be no problem an Arduino would solve this in 30 minutes.
Mr Al,I could probably help, but i need to know a few things.
To start, can you operate this off of a wall wart or does it have to be batteries?
It will be much easier if you can operate off of a wall wart. That is because then we can use an Arduino which allows for a much faster development and probably a lot cheaper too.
Hi Mr Al,Well if you want to use a microcontroller then you have to first get one.
Do you think you want to start with the Arduino or do you want to use all discrete logic?
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