Re: Need Circuit Design -- Cheap...

On Mon, 20 Apr 2009 11:43:56 -0500, John Fields
<jfields@xxxxxxxxxxxxxxxxxxxxx> wrote:

On Mon, 20 Apr 2009 10:46:16 -0500, John Fields
<jfields@xxxxxxxxxxxxxxxxxxxxx> wrote:

This should work: (View in Courier)

. +5V
. |
. +---+---+---------+------+----------+-[+10µF-]-GND
. | | | | |K |8
. [10K] | [Rt] [10K][1N4148] +---+---+
. | | | | | 2|_ Vcc |3
. |U1A| +-[100nF]-+------+-----O|T OUT|---+-----+
. VARM>--|--|+\ | 6| | | |K
. | | >-+ +5--[1M]--+---|TH 7555|[COIL][1N4001]
. +--|-/ | | 7|_ | | |
. | | | +--O|D | GND GND
. | GND | | +---+---+
. | | [200nF] |1
. | | | GND
. | | GND
. | |
. | | +5
. | | |
. | | +---------+-----+----------+-[+10µF-]-GND
. | | LM393 | | |K |8
. | | U1B [10K] [10K][1N4148 +---+---+
. | +--|-\ | | | 2|_ Vcc |3
. | | | >--+-[100nF]-+-----+-----O|T OUT|---+-----+
. +-------|--|+/ 6| | | |K
. | | +5--[1M]---+---|TH 7555|[COIL][1N4001]
. [39K] [Ct] | 7|_ | | |
. | | +--O|D GND | GND GND
. GND GND | +---+---+
. [200nF] |1
. | GND
. GND



The values of Rt and Ct will depend on the flash rate of the LED, so
post the rate and I'll post the values.

Relays are Hamlin HE721A0500.

Send the check to:

John Fields
8905 Bluegrass Drive
Austin, Texas 78759

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Oops, hold the check...

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This seems to work:

JF
.

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