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Say Larry..
"Roger Long" wrote in news:46b66da5$0$8977
: http://home.maine.rr.com/rlma/MOB.htm "I also found this nifty little light. Press or hold the switch and it strobes. Press it again and it can be used as a steady flashlight. Twelve bucks. The tiny little module (see insert) will weigh almost nothing on the pole and is all ready to be wired to batteries in the bottom and a switch. The light module weights less than the quarter next to it and is bright enough to light up a room." I copied this paragraph from your webpage...... Notice how you have to HOLD the switch CLOSED to get it to go into strobing mode? What happens when the switch gets a little old and holding it down results in a noisy connection is the IC keeps seeing intermittent presses, not a steady-state hold down for X seconds. One little intermittent interruption when your finger moves is enough to reset the timer that's trying to time down into strobe mode. It's a stupid design with such cheap switches. Clip a jumper wire across the reed switch and see if it doesn't start strobing reliably. If so, it's the reed, even though it will read fine on an ohmmeter which cannot see the pulsing probably going on. I bought a whole bunch of these little 3 really bright yellow LED "Emergency Flashers" from a flea market dealer. He wanted $1 each, but sold me the whole box for $10, what was left. I've given all of them away except what I wanted to keep. The button in it is unreliable in this same way. It's a rubber switch pressing on the circuit board pads. Its sequence is a little different than yours. One press gets a "steady on" light, which is an optical illusion because the LEDs are actually switching on and off at a very fast rate, 50% duty cycle, to save batteries. Press it again and the flash rate goes to about 2 per second at full power. Press it again and SOMETIMES the damned things will turn off....SOMETIMES...(c; The correct term for your observation is called "contact bounce" and has plagued data engineers since before ICs were invented. Most ICs that are forced to interface with humans have a timer circuit at each interface point that takes input, then refuses to take more input until the timer has timed out, several milliseconds, to keep the cheap, noisy switch from giving it 500 button pushes with each finger push. It's called a "debouncer", obviously. Your little light's debouncer isn't timed long enough, now that the switch is crap. ICs are way too fast for their own good....(c; Larry -- Democrats are raising taxes on oil companies by $16,000,000,000. Oil companies don't pay taxes, just like every other company. Consumers pay all taxes, corporate and individual. What's the price of a gallon of regular going to go to to pay $16B more? |
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