RE: Re: Electronics help & Light beam sensors

["Ian B" <Ian@xxxxxxx>]

I will scan it in soon. Unfortunately the scanner is flat and table like an= d
is being used as such. Having read the article again the emphasis is on
cheap and therefore I guess short range.

The Maplin one sounds good though.

As for the switches, it is difficult to say without knowing how they work.<= BR> Get the old meter out and figure out the voltages etc. and we will go from<= BR> there. Check for mains first although hopefully they will be low voltage.
Ian

>-----Original Message-----
>From: psghome2002 [mailto:psghome@xxxxxxx]
>Sent: 23 June 2002 17:27
>To: ukha_d@xxxxxxx >Subject: [ukha_d] Re: Electronics help & Light beam sensors
>
>
>Thanks Ian,
>
>I'd be interested to see the article although I have now just seen a >dual beam break sensor for =A335 on the Maplin web site. I guess it
>might be quicker and easier to try this? It quotes a 30m range with
>relay contact output. It does say indoor use but I guess it should
>be OK in the garage.
>
>On another related query - I've been thinking about how to sense
>when the garage door is open or closed. I could use a set of micro
>switches and relevant levers etc but then thought why not use the
>travel limiting switches in the electric door opener? The main
>gearing cogs have an open and closed limiter which is adjustable and >makes contact with two micro switches. These switches are obviously
>then used to stop the motor when reached.
>
>I'm not sure if I can 'tap' into this switch in parallel and use it
>as an input to HomeVision without affecting the door opener
>circuitry? Would I need to isolate it in some way?
>
>Cheers,
>
>Paul.
>
>--- In ukha_d@y..., "Ian B" <Ian@M...> wrote:
>> Hi Paul
>>
>> I read something recently about beam breaks and the strategy was >in that
>> case to modulate the IR to 36 Khz but then speed things up again >by a factor
>> I don't remember. (Read the article) OK, the on period is again >modulated
>> onto 300 Khz. The net effect of this meant that the system was
>very low
>> power consumption and immune to most IR sources e.g. remotes.
>Direct
>> sunlight might need some shading but that would not be a problem >for you.
>>
>> There was no range quoted but it uses a TSOP or similar and 555 >timers. If
>> you like I can dig out the article and mail it to you or if more >folks want
>> to read about it I will put it up on my site - you guys choose. >>
>> Ian B
>>
>> >-----Original Message-----
>> >From: psghome2002 [mailto:psghome@h...]
>> >Sent: 23 June 2002 14:58
>> >To: ukha_d@xxxxxxx >> >Subject: [ukha_d] Electronics help & Light beam sensors >> >
>> >
>> >I'm trying to make up a combined parking sensor and garage doo= r
>> >safety switch to be fitted to the inside of the door frame and=
>> >looking across the opening (double garage width). I imagine th= e
>> >output to be linked to HomeVision which, in turn, will allow m= y
>> >Comfort system to close the door (or not) depending on any num= ber
>of
>> >factors I choose to program. I'll also have a couple of high >> >intensity LEDs (red and green) mounted in a box on the far end= of
>> >the garage wall so I can tell when the cars are far enough in = to
>> >close the door (or if there's an obstruction).
>> >
>> >The signalling, interface to the electric garge door and LED's= are
>> >pretty simple and not a problem but the light beam sensor is. = I
>> >bought one of those Velleman kit form beam break sensors that = uses
>> >two IR LED's (transmit) and a single receive LED. Unfortunatel= y
>the
>> >range is about half of what I need. I'm also wondering if IR b= eam
>is
>> >the best technology to use (poss interference from remotes, >sunlight
>> >etc)?
>> >
>> >The transmit circuit looks pretty simple with just a few
>resistors,
>> >capacitors and three transistors. Might it be possible to boos= t
>the
>> >transmit power enough using this circuit, or should I look for=
>> >another sensor - I've had a look at what RS offer but most of = them
>> >are pretty expensive and only a few offer the range I need. >> >
>> >Any thoughts / suggestions?
>> >
>> >Thanks,
>> >
>> >Paul.
>> >
>> >
>> >
>> >For more information: http://www.automatedhome.co.uk
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>
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