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Help with information about electronic parts

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Bob J

New Member
Hello All,
I know enough about electronics to know that I don't know enough. I'm trying to build a motion detector device to trigger my irrigation system so that the deer who are eating my garden, will hopefully move on. I came across an article by Hap Pleasant in which he designed such a device. I've tried to contact him but without a current email address, I've not been successful. The problem is that his parts list has several parts that no longer show up in the Allied online catalog. I'm hoping that someone in this forum can help by giving me current numbers or at least indicating the characteristics of which I should be aware. e.g. for the resistors, what wattage should I be buying? I have attached a parts list, a schematic, and a photo of the device. The parts that I'm having a problem with are: 555 Timer IC, SPST Mini Switch, 25K potentiometer, 10, 100, 1K, and 15K ohm resistors. Can someone help?
Thanks, Bob
 

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Chippie

Member
not sure of your location, but I guess the US?

I guess you should be able to get all the parts you need from Digikey...

1/4 watt resistors should suffice

The 555 timer chip is readily available from most electronic suppliers
 

smanches

New Member
Even Radio Shack carries 555 timers. I was just in there yesterday and noticed them.
 

confounded

New Member
the resistor for the power on LED could be a little higher as its providing quite a high current for the power on LED, maybe make it 220

both LEDS actually
 
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Bob J

New Member
Thank you for the responses. Where my confusion comes into play is in the great variety of parts that look or are called the same. eg. the 555 timer seems to come in a variety of models, but if they're all essentially the same, no problem. I live in Victoria Canada and although we used to have Radio Shack in Canada, they are now "The Source" and have really cut back on their electronic parts. Those that they do have are priced about 10 times what I've seen in the US.

Bob
 

Boncuk

New Member
Hi Bob,

use 330Ω (20mA forward current) for both LEDs. (power and alert)

Addionally move the (vertically drawn) 1N4001 diode from ground to the relay coil for faster EMF recovery. (cathode as drawn and anode to the other end of the coil.)

Use 10nF (0.01µF) from pin5 (CV) to ground.

There is no special component used in the circuit and if Radio Shack Canada charges the equivalent gold price for those parts try to find out a local electronic shop. All components shouldn't be more than US$5.



Boncuk
 
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Boncuk

New Member
the resistor for the power on LED could be a little higher as its providing quite a high current for the power on LED, maybe make it 220

both LEDS actually
At 220Ω and 9V the LED forward current is still too high. (30mA)
 

Boncuk

New Member
Hi again,

I came to the conclusion that the design needs to be revised.

There is no decoupling device included which will make the entire circuit a "perhaps" circuit.

The timing capacitor with 470µF is also pretty huge. The entire time span of 15+25K and 470µF is from 7.75 to 20.65 seconds.

Attached is a revised circuit with proper decoupling and adjustable ON-time from 5.16 to 32.63 seconds.

Boncuk
 

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Bob J

New Member
Thank you so much for all your answers, and especially to you, Boncuk for all the work you put into the circuit upgrades and for giving me the updated diagrams. I really like the variable timing feature as sometimes, depending upon water pressure, it takes a little longer to get the irrigation system running at full tilt. Now all I need to do is study the diagrams to figure out how to put this all together. Bob
 
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