Help!!!!! What is in the box?

Hi Guys,

I have the following problem.

I have a service counter which is not permanently manned.

When a customer enters the service area I would like a passive infrared sensor to detect that someone is there.

A light needs to be switched on in the general office area and some audio beeping or buzzing sound needs to be made until a person attends to the customer. The person attending to the customer would press a button located at the service desk switching the light and buzzer off and resetting the PIR until the next customer arrives.

What goes into the black box to make this happen?

Any help will be greatly appreciated.

Regards

Manie

Any flavor of micro controller or a handful of mixed logic gates would do the job. A micro would be smaller but it would need to be programmed. Using discrete logic wouldn't require any programming but would take up more room.

You could almost do it with an SCR (Silicon Controlled Rectifier) where the PIR triggers the SCR gate, and the switch resets the SCR, but you would need some front end logic on the PIR so that it doesn't re-trigger if the person is still standing there and the button has been pressed.

Get the a PICAXE. Don't even need to program if you don't want to...you can use flow charts. You will need a relay or transistor for the lamp.

Can the push button location reset the 'black box' while customer(s) still being sensed ?
Duration or repeatability of beep ?

Hundreds of types, some may fit your needs.
Evaluate this : ----> **broken link removed**

The light needs to flash/be on until the push button is pressed to switch it off.
The beep is a short 2-4 sec beep when the light is switched on and not repeated.

Maniecoe said:

The light needs to flash/be on until the push button is pressed to switch it off.
The beep is a short 2-4 sec beep when the light is switched on and not repeated.

Click to expand...

I believe this meets your needs...

This assumes the PIR sends out a 5v when it detects some one. Note that had to be drawn as a switch.
The light will stay on (thanks to the flip flop)
The flip flop triggers the 555 timer for 3 or 4 seconds even if the flip flop stays on.

The reset button is obvious.

Do you want to build something from scratch, or wire together commercially available products (as much as possible). If the latter ...

Start with a motion detector from Home Depot or wherever, with wires running to the light. Those wires go to a USB wall wart and through a DPDT relay to the light. Now you have a 5 V source that comes on when someone walks in. That powers the beeper and the flipflop that turns off everything. As above, when you press the button, the ff is set. The ff output turns off the beeper and energizes the relay to turn *off* the light (the light is wired to the normally-closed contacts. When the lobby is empty, the PIR goes to the off state, and power is removed from everything.

ak

I think that the over-helpful forumites have gone far too high-tech.

PIR sensors are available in nice robust boxes, designed to turn lights on, so they have 110 / 240 V power and outputs. Lights and buzzers are available with 110 / 240 V power.

All you need for the logic a 110 V / 240 V relay. A suggested circuit is shown. When the PIR turns on, it turns on the relay, light and buzzer. The relay contact then powers the relay, light and buzzer until the reset button is pressed.

Typical relay

Typical switch

You need all the components to be rated for the local mains supply voltage. The PIR should be a 3 wire type. The reset button needs to be a normally closed one, but all "stop" buttons can be wired like that.

The PIR has to be set for its smallest time.

There is no timer so the buzzer will run all the time once triggered.

Like the other designs, you need an "escape route" to avoid triggering the PIR as you leave the service area.

If you get a latching stop button as the reset button, and leave it latched down, the light and the buzzer will operate briefly when a customer is seen.

I put togther something like this for a shop, not the same but I'll mention it anyway.
A pir sensor int the shop activated a buzzer and light upstairs in the workshop.
The door into the shop had a normally closed switch, so that when the door was opened it silenced the buzzer, but the light remained lit when there was movement.
The shop assistant left the door open while serving, so as not to annoy those working upstairs, but they could still see if someone wa sin the shop by the light.
No reset button required.

Wrote this yesterday, forgot to post it...

Diver, that's where I was headed, but with NC relay contacts instead of a NC switch. I didn't like my solution but it was late and I wanted to get the basic idea out there and tweak it later. You beat me to it.

ak

like 20 yrs ago i bought a pir chime that rings when someone passes it , or alarm sounds until you shut it off, it cost like 20$ ... not a single employee got past my gate without a thorough searching of the lunch box for bombs ... seriously, that was my only task as the security detail... and not a single bomb.. or lunch ... got through on my watch, which i mostly did from the back of my eyelids