circuit design help: momentary switch activates/cancels electronic switch

[circuits snipped]

Boy, that sure is a lot of stuff, when it could be done with an RS flip-flop.

Cheers! Rich

Does RS even sell chips any more?

;-)

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

View in a fixed-width font such as Courier.

. . . 12VDC>---+-------+-----+-------+ . | | | | . | | | 12VDC | . | | --RELAY--- . | | |\\ COM| . | - |/ | . | ^ |\\ | . | 1N4001 |/ NO | . | | ---------- . | | | | . o +-----+ +-----+ . -| SWon | | | . o | | | . | | | | . +----[2.2K]---|-------+ | . | | | . [2.2K] | | . | | LAMP . | ||- | . +-------+--||< IRF510 | . | | ||- | . o === | | . -| SWoff 0.1U | | . o | | | . | | | | . +-------+-----+-------------+ . --- . /// . . .

IF your load is inductive, non-resistive, or capacitive then something like this would be better: View in a fixed-width font such as Courier.

. . 12VDC>-------+----+---+-------+-----+-------+ . | | | | | | . | | | | | 12VDC | . | | | | --RELAY--- . | | | | |\\ COM| . | [10K] | - |/ | . | | | ^ |\\ | . | | | 1N4001 |/ NO | . | | | | ---------- . >| | | | | | . 2N3906|--+---|-[10K]-+-----+ | . /| | | | . | o | | . | -| SWon | | . | o | +-------+ . | | | | | . | | | - | . | | | ^ | . | [2.2K] | 1N4001 LAMP . | | | | | . | | ||- +-------+ . +--------+-------+--||

Allowing for pressing both switches simultaneously, make this change: View in a fixed-width font such as Courier.

. . 12VDC>-------+----+---+-------+-----+-------+ . | | | | | | . | | | | | 12VDC | . | | | | --RELAY--- . | | | | |\\ COM| . | [10K] | - |/ | . | | | ^ |\\ | . | | | 1N4001 |/ NO | . | | | | ---------- . >| | | | | | . 2N3906|--+---|-[10K]-+-----+ | . /| | | | . | o | | . | -| SWon | | . | o | +-------+ . | | | | | . +--------+ | - | . | | ^ | . | | 1N4001 LAMP . [1K] | | | . | ||- +-------+ . +--------+-------+--||

Terry Pinnel wrote: "Hey, how about an even simpler approach: a single toggle switch?"

--------------------

if you can find me toggle switches that fit inside the switch housings on my motorcycle handlebars, that would be great. please post link. :)

LOL!

But, just because I'm in a bluff-calling mood, yes:

(mind the wrap)

Cheers! Rich

Only the analog stuff, LM339, LM324, TL082, 555, 556, LM386, LM317,

7805, 7812, maybe some others, transistors, diodes, resistors, caps, etc...but no digital IC's whatsoever available in the stores.

You might try one of these:

Good Luck! Rich

A rocker switch would be best for light circuit control on a motorcycle. These come in momentary also and can be controlled by thumb. One way using readily available parts is shown below. When the rocker momentary is moved to BATT position, voltage is applied through D1 to RLY1 and R1 to the transistor base turning both components on. D2 prevents load current from flowing through the miniature switch. When RLY1 activates, BATT is thrown onto the load ckt through the COM-NO contact closure, and BATT is also applied through D2 to RLY1 and R2 to the TIP31 base drive. SW1 can now be released and the circuit remains latched on. When SW1 is moved to the GND position, junction of R1-R2 is pulled to GND removing TIP31 base drive and turning it off. D1 prevents current flow from the RLY1 NO ckt from flowing to GND. RLY1 cuts off, removing voltage from the load and RLY1. The SW can now be released and the circuit remains off. D3 suppresses RLY1 coil inductive flyback, and D4 kills transients from the load wiring. R3 is a leakage drain resistor for the TIP31.

View in a fixed-width font such as Courier.

. . +---+ +-----------------------------+---->

. | | | | . -+- | | | TO LAMP_CKT . /// | | +---->

. GND | | . +-----------------------WTHR_PROOF_ENCL---+ . | | | | . | +---------+ | | . | | | | . | | 1N4001 | 1N4001 | . | +-----|>|-----+---|>|---+ | . | | D4 | D2 | | . | | | +-----|--------+ | +---------+ . | | | | | | | | | . | | ------- | | | | | . | | |NO COM| | | | | | . | | RLY1 | | | | | | SW MOM | . | | | | | | | | ROCKER | . | | | | | | | | +-----+ | . | | +--|-/\\/\\- |---+ | | | | | | . | | | ------ | +--|-------+ | o--|-+- BATT . | | TIP31 | D3 | 1N4001 | | / | . | +-E C--+---|>|--------+--|

"You might try one of these:

Good Luck! Rich "

-------------------------------

Thanks for the reply rich. I already have nice switch housings and swiches that fit in them and look nice. they are momentary switches. the switches are already in place...the bike wiring is all custom and right now I am working though turn signals and running lights and such.

I am not sure how google would help me at all in the case since i spent a LONG time on google before I posted here.

Will post what I came up with when I am done with it.

--
If the switches are Normally Open, you could use another small SPDT
or SPSTNC relay to supply the normally closed contacts you\'d need
for the circuit I posted earlier.  Or, you could use an RS latch, a
transistor, and a SPSTNO relay to do the trick instead.  Want a
schematic?

"matthewuw" wrote in news:1129097288.402163.260420 @o13g2000cwo.googlegroups.com:

something

this?

, all kinds of electronic switching for low volt/current applications . roma