Inductor Size for BasicStamp in Automotive application

David H.

Hi there,
I'm working on an application using the basic stamp 1 in a vehicle.· It will control the sequencing of the taillights with 3 LED taillight bulbs on each side.· I believe I should an inductor inline to stabilize the Stamp.· Are there any recommendations for the size of Inductor?
Thank you for any and all help.

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David


There are 10 types of people in this world,...
Those that understand binary numbers, and those that don't!!!

Post Edited (David H.) : 5/8/2008 1:40:13 AM GMT

David H.

I'm a newbie with Basic Stamps and circuits, and would appreciate any help.· I searched the forums and found a similar application an they used a 100mh inductor.· I tried these, and it didn't allow enough power to fully light the LED bulbs the way it should.· I'm wondering if it should be 100uh, or the power to the bulbs need to bypass the inductor so the stamp gets the power through the inductor only.· Any suggestion or ideas?·

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David


There are 10 types of people in this world,...
Those that understand binary numbers, and those that don't!!!

allanlane5

I'm pretty sure the BS1 is as current limited as the BS2 -- you may need an additional transistor to switch enough current to fully light the LED bulbs. Without a schematic, we can't be much help.

All the inductor does is prevent the current flowing through it from changing as fast as it could without the inductor. You may also need a 10 uF capacitor near the BS1 in order to filter out voltage spikes -- you probably need both the inductor and the capacitor, in other words.

David H.

allanlane5
Thank you for a little insight. I uploaded the schematic. I'm using solid state type relays to control the LED taillight bulbs. I used to have the inductor inline after each fuse on the input lines. I believe if I put the inductor back in, and then run power before the inductor to power the relays should work. I think the inductor must of limited the power surge required to light the bulbs properly.

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David


There are 10 types of people in this world,...
Those that understand binary numbers, and those that don't!!!

Beau Schwabe

David H.,

I'm curious why you think that an inductor will solve your problem. A simple diode-capacitor filter should be plenty to ward off a noisy voltage supply and stabilize the Stamp.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

David H.

Beau,
I thought an inductor should be used from reading previous postings. So the diode, and capacitors that I have in the schematic along with the voltage regulator should be all I would need for an automotive situation?

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David


There are 10 types of people in this world,...
Those that understand binary numbers, and those that don't!!!

Beau Schwabe

David H.,

Observe polarity, and place a cap (470uF or so) directly across VDD and VSS on the Stamp, and yes that should be all that is necessary.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

David H.

Beau,
Thank you VERY much. This will make things a little easier.
I really appreciate your replies.

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David


There are 10 types of people in this world,...
Those that understand binary numbers, and those that don't!!!