Timed Switch Assembly - RC Groups
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Jan 26, 2009, 08:31 PM
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Timed Switch Assembly


Hello there.... I am looking for a manufacturer that either has this timed switch or can make them for me. I am looking for aro 25 to begin with and maybe more if they work well. the specs are

2" x 2" .... 1/2" height
push button on
push button off
timer with Potentiometer to adjust the time.... up to 20 mins
input 11.1 volts ( 3 cell lithium )
low voltage cutoff... 9v


approx load on the switch is 100Mah draw over 10 mins.... 10 Mah/min

I know there are some switches that are close to this out there in kit form... but I am not the most proficient person at soldering, so I am looking for a completed unit.

Suggestions ?
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Jan 26, 2009, 08:57 PM
R/C Electro-Gadgeteer
Tomapowa's Avatar
Curious, what did you plan on switching? The power from the battery to a load? How accurate did the timer need to be? Does the on/off switch you mentioned control power to the timer only or to the complete circuit? (i.e. also cuts power to load). Also, are you requesting two buttons (one for on, the other for off) or is it a simple on/off switch as I assumed?
Jan 26, 2009, 09:17 PM
Registered User
timer accuracy is not critical... approximate 15 - 20 mins.... if there is a potentiometer then it can be adjusted... the on / off controls the output and also starts the timer when turned on.... when the timer gets to 0, then the output is shut off and the timer is reset to start again.
Jan 26, 2009, 11:00 PM
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BushmanLA's Avatar
Quote:
Originally Posted by plasticjoe
timer accuracy is not critical... approximate 15 - 20 mins.... if there is a potentiometer then it can be adjusted... the on / off controls the output and also starts the timer when turned on.... when the timer gets to 0, then the output is shut off and the timer is reset to start again.

You can probably achieve something like this with one of those old 110V timers for coffee pots etc.
Jan 26, 2009, 11:00 PM
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Ron W3FJW's Avatar
Sounds like a fairly simple NE555 use to me.
Jan 26, 2009, 11:02 PM
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where can I get that ? like I said... I am not the circuit board whiz... is there a place I can get those specs in a board ? or a place that can make those specs for me ?
Jan 26, 2009, 11:42 PM
R/C Electro-Gadgeteer
Tomapowa's Avatar
Come on guys... Since when does a 555 timer or a coffee timer measure battery voltage (A/D) ????

He also wants a Low Voltage Cutoff (LVC) integrated with the timer function. This certainly can be made using an 8-pin PIC such as the 12F683, along with a few switches, resistors, V-reg and a transistor/MOSFET. PlasticJoe, you are not going to find an off-the-shelve solution that meets your unique requirements... it's certainly a custom product. What are you willing to spend on development and fabrication? Also, what other products out there "in kit form" did you say was similar?
Jan 26, 2009, 11:48 PM
R/C Electro-Gadgeteer
Tomapowa's Avatar
One last question PJ,
You mentioned "approx load on the switch is 100Mah draw over 10 mins.... 10 Mah/min". The more important spec is maximum current draw (instantaneous). What are you going to be powering? This is important as you will either need a small switching transitor (control loads up to 600ma) or a MOSFET (control loads that draw "amps" vice milliamps).
Jan 27, 2009, 03:11 AM
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AleG's Avatar
Well, I guess in functionality it's similar to the electric free flight timer I designed, the BirdBrain, run time can be thought as on state, it has low voltage cut off and is a operated with a single button.
I'm quite sure it could be easily modified to meet the requirements.
Jan 27, 2009, 07:45 AM
Registered User
I am currently using this and it works ... but I think it's a tad overkill... and I am not the soldering whiz, I am ok at it... and it's a tad expensive to be included in the unit I am making
http://www.canakit.com/60-minute-1-h...-uk191m60.html
as far as the "maximum current draw" there are no spikes at all... it's an on... and that's it... same current flow from the power on to the power off
Jan 27, 2009, 10:52 PM
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Ron W3FJW's Avatar
That's a cyclic timer. If that works for you, is that what you want? It's different than what you specified in your OP.

When power is applied it's:
ON period from 6 seconds to 60 minutes
OFF period from 6 seconds to 60 minutes
and then repeats until power is removed.
Jan 28, 2009, 07:12 AM
Registered User
the way it's been working for me is that it kicks on when the button is pressed and then it shuts off when the time hits... never had it kick back on tho.... I just want a timed on.... and then once that time hits...an off
Jan 28, 2009, 11:43 PM
R/C Electro-Gadgeteer
Tomapowa's Avatar
plasticjoe,
A work in progress... hopefully I'll get some code working this weekend.
This design does not use a potentiometer (just another mechanical device to fail). Timer duration (stored in EEPROM also) would be programmed using the pushbutton (same button used to enable/disable the timer/switch function). # of LED blinks would indicate timer duration (1 of 6 settings: 5, 10, 15, 20, 25 and 30 minutes). After programmed (enabled by by holding down button upon powerup) the timer/switch function would be enabled by pressing the pushbutton (LED turn on). To turn off the timer manually, you would hit the button again (like a toggle). Upon the timer expiring, it would turn off the LED and disable the switch. The LVC function would constantly monitor the battery voltage and when below 9volts, it will turn off the timer/switch if enabled (maybe even flash the LED rapidly until you remove power... just so you know the LVC kicked in instead of the timer expiring). I'll try to report back here as I make progress. Feel free to post other ideas/comments...

(POST NOTE: I had a small PCB error... the transitor's E and C were backwards on the PCB... I since updated the PCB file...)
Last edited by Tomapowa; Feb 03, 2009 at 02:13 AM.
Jan 29, 2009, 05:22 AM
Registered User
Almaz's Avatar
Tomapowa!
This is a nice looking design you have. I was wondering regarding 33k and 10k resistor. I might be wrong but I think using these resistors might give improper ADC reading. Maximum resistance for adc input should be 10k. 0.1 capacitor might be better to use with these resistors. Anyway, Great Job!
Jan 29, 2009, 07:18 AM
Registered User
I am impressed ! Sounds great to me !! I am eager to hear more !


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