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the12volt's install bay
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 Topic: momentary switch and two output
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buzz-wwp
Joined: January 25, 2012
Location:
South Carolina,
United States
Posts: 1 |
| Posted: January 25, 2012 at 1:49 PM - IP Logged |
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I am trying to install a momentary switch that cycles between output 1, output 2 and off with relays. I have looked thru the diagrams and can't find what I think I need but not sure I would know it if I saw it.
Know barely enough to be dangerous, can some one steer me in the right direction?
Buzz |
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oldspark
Joined: November 03, 2008
Location:
Australia
Posts: 2,856 |
| Posted: January 25, 2012 at 6:26 PM - IP Logged |
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The easiest (other than a specific mechanical switch) is probably a 4017 "one of ten output" counter circuit.
The switch clocks the 4017. The switch will probably need "debouncing" - often a mere resistor & capacitor.
The normal output is output #0 (pin 3; using output 0-9 convention and NOT the 1-10 "labeling"). Leave that unconnected (ie, nothing on).
A clock (switch) to pin 14 sends output #1 (pin2) high.
The next pulse turns #1 off and #2 on (pin 4).
By connecting the next output #3 (pin 7) to Reset (pin 15) means the next press resets the counter/4017 back to #0. (Output #3 does go high for about a micro-second, but that has no impact in this case.)
The 4017 outputs can only supply ~30mA so some buffer will be required to drive a relay. (IE, a transistor, though a FET/MOSFET may be simpler. And it may be simpler and better for the FET/transistor to ground the relay(s).)
A diagram is so much simpler than the above....
The 4017 operates (from 3V) to 15VDC, so +12V limiting (and filtering) should be added - maybe a diode and capacitor.
A 3-terminal voltage regulator up to (say) 9V may be best - eg, 7805 for 5V, 7809 for 8V - with a few diodes (polarity and capacitor discharge protection) and a cap. [If the relays are ground-switched, then the voltage of the relays is irrelevant - as long as the relays and 4017 share the common ground.] BTW - the selected voltage depends on different factors - eg, FETs may need ~5V to turn on; the regulator may have a voltage drop up to 3V; your battery may be as low as 11V - hence 11V - 3V = 8V, so 5V to 8V.
Actually I'd probably use the settable 3-pin LM317 regulator. Not so much for its 2 resistor programming (one is 120Ω, the other is chosen to get the voltage you desire), but for its current limiting and self-protection. And its "one regulator for all". And it can be used as a current limiter (eg, for LEDs etc).
Sorry for all the above text, but I'm thinking aloud. Again. If I had my old circuit diagram I'd simply post that. (Recent data loss & I haven't yet recovered. In fact, I may never bother to recover it... LOL.)
But if you want to read the following optional extra crap...
The 4017 for a "divide by n" counter is easy - just connect its reset pin to the "n" pin (where the "n" pin is the 4017 output 0-9, eg, yours is div by 3, hence connect Reset to output #3 (pin 7). [It's the "n+1" pin if using the output 1 to 10 convention.]
"n" can be 2 to 10 for one chip, but n can be much higher by cascading (adding) the required number of 4017s. (It has a "carry out" pin (#12) that makes this easy but connecting it to the next 4017's "clock enable" pin (#13).)
The 4017 circuit is great for future expansion or for uncertain cases - eg, you want to add another press for another output, or you think your Harley tacho on your car engine means a divide by 2 counter but find it should be divide by 4 - just move the rest pin connection (and add the output circuitry in your case).
BTW - for divide-by circuits, I usually use output #1. Then it is not "normally" on (as per output 0) and I don't have to move the output if I change the divide-by number.
[ I once used a 4017 to convert a normal car distributor to sequential spark. Output 0 was unused, IgCoils for splugs 1, 3, 4, 2 (for a 4 cylinder) were outputs #1, #2, #3, #4; with the clock from the dizzy output (points, pickup, or igniter) and the Reset from an extra "synch" sensor in the dizzy. ]
And if you decide for key-press #4 to be "both outputs #1 & #2, move Reset up one to #4, add isolating diodes (small common IN914 or 1N4148 etc signal diodes, else 1N400x etc) between outputs #1 & #2 and their buffers, and 2 diodes (ditto - 1N914 etc) from output #3 - one to the #1 output and one to the #2 output (each AFTER the previous "isolating" diodes to the buffer/relay-driver). (That's how to "logically-OR" outputs - eg, relay #1 is output #1 or #3; relay #2 is output #2 or #3.) [Damn, where's that diagram with descriptive? It was so good...!]
Whoops - I digressed again....
Though I dislike using a chip (IC; 4017) for simple counters, it is often the simplest. EG - though a "divide by 2" circuit is easy with a few transistors etc, SAAB and others use the 4017 for their high-low beam circuit! But for divide by 3 (as per yours) or higher, the 4017 is best.
And whilst I find using multiple relays as per another thread (over 150 relays for a "5 counter" circuit), I much prefer using ICelectronics plus the output relays (ie, 10 or 15 relays instead of >150 relays). But some prefer the alleged
simpler relay version.
Note to self: Hey OldFart, recover that lost data so you can continue that Harley tacho in hot-rod conversion... |
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