Electronics > Beginners
HS8A005(BISS0001) Light On Time
Jwillis:
Friend of mine wants to increase the time ON for a light with this motion detector. Right now it only shines for about 20 seconds and he would like about 2-4 minutes .Theirs no adjustment but I'm thinking that if I increase the value of R7 that should do the trick.
Now from what I understand the 56nF cap is charged by pin 4 then when theirs a trigger C3 discharges across R7 into pin 3 keeping pin 2(Vo) High for a period of time until C3 is discharged.
Am I correct in my thinking?
https://cdn-learn.adafruit.com/assets/assets/000/010/133/original/BISS0001.pdf
Kasper:
Looks like you'll want to change R10 or C6.
From your link:
Tx: time duration during which the output (Vo) remains high after triggering.
Tx ~= 24576 x R10 x C6
Jwillis:
For some reason my first post didn't include my attachment.What am i doing wrong?
Rigolon:
Can't be sure just looking the photo. But check if R7 terminal is at same node as Pin 4 and C3.
Anyway, for me it also looks possible that it's going to R8, and the schematics doesn't show this connection.
See the orange circle in attached image. It looks like there is a track right in the middle of the circle.
--- Quote from: Kasper on December 25, 2019, 09:03:19 pm ---Looks like you'll want to change R10 or C6.
--- End quote ---
@Kasper, from picture posted later it seem that PCB and Schematics have different annotation.
Jwillis:
--- Quote from: Rigolon on December 26, 2019, 04:27:13 pm ---Can't be sure just looking the photo. But check if R7 terminal is at same node as Pin 4 and C3.
Anyway, for me it also looks possible that it's going to R8, and the schematics doesn't show this connection.
See the orange circle in attached image. It looks like there is a track right in the middle of the circle.
--- End quote ---
Just a badly cleaned board. See attachment
The first problem I'm having for some reason not all of my post is being uploaded. weird.
What I'm having trouble with is at pin 3 and pin4 the values marked on the photo would give the right time . But the true values are 47K at pin 3 .It's Marked Code is 473 and measures close to 47K .
At pin 4 my measurement has to be wrong for I get conflicting values at different test frequencies.At 100hz C3 is 6uF . 1kHz is 510nF ,10kHz is 30nF , 100kHz is 10nF
I guess I'll have to pull the cap and test it then .
The other problem is the formula given on the data sheet doesn't explain the magnitude of each value . Is the time in seconds ,mili seconds ,micro seconds ? Is the capacitor in nF ,uF ,F ? Is the resistor Kohms ,Ohms ? I put the values in the equation because they just happen to work but actual values don't make any sense.
Also the data sheet refers to a "timing chart" . Wheres the timing chart on the data sheet ?
Sorry about confusing everyone but this is frustrating when data sheets are crappy.
On a happy note I'm really pleased with my new microscope.
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