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Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
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You have to show connections, and don't use the tab key; use the
spacebar instead.
From what you've said so far, it appears this is what you have:
(View in a fixed-pitch font like Courier)
. +------+---------------------------+
. | | |
. | [10R] [20R]
. |+ | |
. [BAT] +------+------+------+ |
. | | | | | |
. | [LED1] [LED2] [LED3] [LED4] [LED5]
. | | | | | |
. +------+------+------+------+------+
1. What is the battery voltage?
2. Is there an ON-OFF switch anywhere?
Where?
3. Are the resistors shown in the correct locations?
3. Are the resistors brown-black-black-gold and red-black-black-gold
or brown-black-brown-gold and red-black-brown-gold?
Or something else?
in the ON position, the flashlight array will throw a steady light and the red LED will be dark.
In the OFF position, both the flashlight array and the red LED will be dark.
In the BLINK position, both the white LEDs and the red LED will flash at the same rate.
That is, providing the LED looks like a low-valued resistor when it's on and a high-valued resistor or an open circuit when it's off. If it doesn't, then the circuit won't work.
Earlier, I made the assumption that the flashing LED was dropping about 1.2V with 165mA through it, but neglected to add in the drop for the flashing circuitry, of which the pass element is in series with the lamp.
The problem is, after having looked at several blinking red LEDs, their voltage drop is all over the place and, not knowing which one yours is, there's no way to tie down the value of R6.
If you have a voltmeter you can measure the voltage across the red LED when it's on and then figure out the value of R6 like this:
That'll give you the value of R5 for 20mA into the base of Q1, which should be enough to let the red LED flash and flash the rest of the LEDs as well.
If you don't have a voltmeter, I'd guess at about 2V across the LED when it's on, and about 0.7V across the base-to emitter junction of Q1. Then R5 would be:
91 ohms is a standard 5% part and should work well if the LED will flash with 2V across it.
If it won't, try lowering the value of R6 until it does.
BTW, I have all the parts on hand and they're just pennies, so if you email me with someplace to send them I'll just pop them in the mail and save you the hassle of having to buy them.
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