Parallax SSIR Details

Steve Joblin

A few of us have been Private Messaging about the SSIR.· It is really a very cool device in freeing up Stamp pins.· The documentation does not have a parts list, nor a schematic.· Can Parallax provide a quick parts list and schematic that would allow Stamp Enthusiasts to "roll their own"?· Thanks so much!· If Parallax is willing to provide this information, I promise that I will buy the parts from Parallax in an effort to continue to support their efforts (I hope that others will also be as respectful and do the same!).

Thanks,

Steve

Stephen Swanson (Parallax)

Steve,
······· Here is the schematic and parts list, you will want to follow the drawing for the left and right gripper detector.
Parts list:
D1 - 1n5231
R1 - 470 ohm
IR Transmitter w/ heat shrink tubing
Infrared Receiver

If you have any questions just ask.

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Stephen Swanson
Technical Support
Parallax, Inc.
sswanson@parallax.com

Russ Ferguson

Stephen:

I will be very interested to get this circuit bread-boarded and compared with the circuit in the thread that has a transistor.

I do have two questions.

#1. The 1N5231 is a Zener diode with a reverse breakdown voltage of 5.1v. The circuit shows that the Zener is oriented the same direction as the LED. The LED will not respond to a reverse polarity even when the Zener has the reverse bias voltage of 5.1 v across it. What is the function of the Zener diode?

#2. The specs for the PNA4601 lead me to think that when it 'sees' the modulated IR light, it will provide a parallel low resistance path to ground for the stamp pin that would otherwise be powering the IR LED. It seems that this would limit the effectiveness of the circuit.

Stephen Swanson (Parallax)

Hi,
··········· The Zener is not actual being used for its 5.1 reverse breakdown. But more for its 3.28vdc drop. This of course could be done with a 1n400 but at 3.44vdc drop the line rests closer to the threshold voltage. Also we have good amount of the Zeners in stock. For the PNA4601 I’m not sure how much it limits the ‘effectiveness’, but if you want a better range then the two pin method (like on the BOE bot) would be a better setup.



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Stephen Swanson
Technical Support
Parallax, Inc.
sswanson@parallax.com

Steve Joblin

Steve Swanson - Two items:

1.· Thanks so much for the parts list, the schematic, and the description about the diode!

2.· Thanks so much for the idea of the SSIR... I was always having to use too many pins for IR... your circuit is a elloquent solution!· Tell the folks at Parallax you deserve a raise!

Thanks again,

Steve

Jonb

Interesting...

Thanks alot for sharing this with the community.

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Post Edited (Jonb) : 4/5/2005 3:43:17 AM GMT