Hi cpemma, since I need up to 24 toggles, I'll be using all circuits. Would an unterminated trigger cause problems for the other or is it just a good idea?
I am also going to give both of the proposed solutions a try. It took a little hunting finding the 74 series chips, the 40** are easy to find.
I am also going to give both of the proposed solutions a try. It took a little hunting finding the 74 series chips, the 40** are easy to find.
Hi cpemme, interesting. I didn't even know about google groups. I see that they progressed back to a transistor based circuit and that sparked a thought.
Ultimately I am driving a mercury relay which will certinly need more than TTL current. If I have to use a transistor to drive it anyway, should I just go with a version of the original two transistor circuit? Do you think the Win's circuit would have problems with debounce? Thanks.
Ultimately I am driving a mercury relay which will certinly need more than TTL current. If I have to use a transistor to drive it anyway, should I just go with a version of the original two transistor circuit? Do you think the Win's circuit would have problems with debounce? Thanks.
If u go to use RC on each 4093, u will end up in 24 of them. I have not suggested both 4093 as it increases number of ICs. For resetting with one power on reset, use 4541 and a driver transistor/gate and connect to all the 4093s. It's very easy to use 4541 and it has power-on reset facility inbuilt.
just download 4541 datasheet and read the application. U just have to connect it in single cycle mode and select Q/Q bar properly.
Self wrote
imix500,
Do not use Tantalums as they burn very easily. Use electrolytics and small ceramics(0.1)
Gajanan Phadte
just download 4541 datasheet and read the application. U just have to connect it in single cycle mode and select Q/Q bar properly.
Self wrote
imix500,
Do not use Tantalums as they burn very easily. Use electrolytics and small ceramics(0.1)
Gajanan Phadte
Have you considered using a microcontroller? A uC will ensure whatever desired power-on state you want, debounce input buttons, and drive all the relays you want. If your control scheme is simple, a 14 or 16 pin PIC with 1 k of memory can easily handle the job. You might even be able to do it with an 8 pin part.
How do you drive 24 relays with a 8 or 14 pin uC? You use a 3 wire serial port and three TPIC power logic shift registers (TPIC6C596 or similar) from TI, readily and inexpensively available from digi-key and other sources.
I_F
How do you drive 24 relays with a 8 or 14 pin uC? You use a 3 wire serial port and three TPIC power logic shift registers (TPIC6C596 or similar) from TI, readily and inexpensively available from digi-key and other sources.
I_F
Hey guys, well I've ordered all parts to build one of each scheme.
I just went with good ol' 2n2222's to drive the relays, athough the transistor arrays would have been cool... maybe next time.
I_Forgot, another great idea with the uC idea. I did a project similar to this for controlling a high pressure air compressor in high school, I'm sure one would work well here too.
So another question, I'm gonna use gmphadte's sketch for both sets of chips. Will the same component values work for both?
gmphadte, the timer will be good for power up reset. I've never used one before but looks straight forward. Is it better than a 555?
Thanks guys.
I just went with good ol' 2n2222's to drive the relays, athough the transistor arrays would have been cool... maybe next time.
I_Forgot, another great idea with the uC idea. I did a project similar to this for controlling a high pressure air compressor in high school, I'm sure one would work well here too.
So another question, I'm gonna use gmphadte's sketch for both sets of chips. Will the same component values work for both?
gmphadte, the timer will be good for power up reset. I've never used one before but looks straight forward. Is it better than a 555?
Thanks guys.
Duo said:
Is too much to suggest to someone who considers themselves to be an electronics hobbyist to actually learn something?
The hardware investment is minimal (if one does a little looking around before buying) and the development software to write the program for the uC is free. There IS considerable investment in time required to learn to do the programming.
Once you "make the plunge" and get the programming hardware (some $25 programmers are available) and get your feet wet with a project or two you start to find all sorts of other things to do with uCs.
I_F
I'm not saying there's anything wrong with the hobby person learning new things, I do it all the time.
I simply feel that if someone wants something so simple done quickly as this thread purports; it might be better done with other methods.
If the hobbyist wishes to spend the time to learn to program and develop the technology he wishes to use; power to him.
I simply feel that if someone wants something so simple done quickly as this thread purports; it might be better done with other methods.
If the hobbyist wishes to spend the time to learn to program and develop the technology he wishes to use; power to him.
Hey guys, first off, thanks to both of you and your help so far. I get where both of you are coming from.
Duo, logic ic's are gonna be the way to go with this one. Yes, learning Pic programming will hinder the completion date.
I_Forgot, the Pic would have been a good way to go if the idea had come into play at the beginning, but I had already married the logic solution. As I mentioned I used a basic stamp (a BS1?) when they first came out to do a simple industrial control app (still being used to this day I believe) but other than that I don't have much experience with uC's. I have, however, always had an interest in them after watching my father work on some Nasa/Airforce simulators. With the expanded capability and lower cost of the newer one's, I'll keep one in mind for future projects. Thanks guys.
Duo, logic ic's are gonna be the way to go with this one. Yes, learning Pic programming will hinder the completion date.
I_Forgot, the Pic would have been a good way to go if the idea had come into play at the beginning, but I had already married the logic solution. As I mentioned I used a basic stamp (a BS1?) when they first came out to do a simple industrial control app (still being used to this day I believe) but other than that I don't have much experience with uC's. I have, however, always had an interest in them after watching my father work on some Nasa/Airforce simulators. With the expanded capability and lower cost of the newer one's, I'll keep one in mind for future projects. Thanks guys.
imix500 said:
???? If the transistor is conducting its Vce should be very low (0.5V?) so whatever the current, the dissipation is very low. Any small-signal transistior able to carry the current should do.
Of course you should take the supply equal (a bit above) the coil voltage. If it is much higher, take a series resistor to take the excess voltage to prevent overheating the coil.
Jan Didden
I_Forgot said:
But learning to program a PIC in order to simplify a circuit is like suggesting the audio amplifier builder should learn to play the piano or read music notation to further his hobby.
Far better to understand how the dumb circuit works IMO.
Any relay coil will have a fairly wide operating range, down to at least 80% nominal, so you don't need to worry about the VCE(sat) drop across the switcher transistor. Just make sure the transistor is saturated by appropriate choice of base resistor.
Take a 2N3904 with min gain of 100; force gain to 50 to ensure saturation, then 200mA load current = 4mA base current, base resistor (on a 12V high) = (12 - 0.7)/.004 = 2825, so 2k7 or less is fine for any load up to the maximum rating.
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