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Bald_N
Opto device probably good for 240VAC isolation if not higher between transistor side and LED...It comes down to track spacing.
Thus 1wire bus 5VDC can switch on the LED and just connect the transistor into the existing cct. i.e. the wires going up to the LCD..
http://img.photobucket.com/albums/v3...onway/opto.jpg
The packaging claims to be able to program all 4 outputs individually. I have not really played around with setting it up. I give it a go in the next couple of days and let you know.
Key Features:
Surge Protection
7 Day digital timer
Reduced standby power consumption
4 individual programmable outlets
4 on/off programs per outlet
2 extra wide transformer spaces
Easy one button program check function
rendom function - sets a random program period of between 10-31 minutes during 0600-1800
Daylight savings function - switch to summertime without resetting the programs and current time
Built-in rechargable battery backup
Current time and date display
LCD screen
Then it cr&ps on about it's uses :lol:
I'm thinking this,
cut a small opening to suit an RJ45, using the 1-wire standard the connections will simply be
+5v (to power the 1-wire cct board only), gnd, 1-wire data.
Inside the power board put a very simple cct board, but carefully insulated from the rest, board is just a ds2408 or ds2450 with opt-coupled outputs. the opto-coupled (or if you like opto-isolated) outputs go to the c945 transistor.
Leave everything else intact but ensure the timer isn't porgrammed to do anything, and it can all be reversed if need be, ignoring the small cut-out of course.
Just saw your post Bad Inferno re: opto-coupler - that's exactly what I was thinking of!
DIYJ by the time we mount 4 optos 4 resistors and a DS2408 its going to take up quite a bit of room...
How do we find out what opto style is required I assume they have two types of outputs NPN or PNP ?
Yeah, that'll work. I have at work some chips that are (from memory), 4 optocouplers in one DIP. I'll get the details Monday when I return to work.
They are from some equipment that has been decommsioned and will never been used again. I've been told I can butcher it if I want.
I can't remember the part number and it's going to bug the $hit out me tonight!
Yep a qaud optoisolator would make it simpler & smaller, I'll do some searching, futurlec has a page of optoisolators so I'm sure theres something suitable from them.
Try PC846 by Sharp. I'm sure these are the ones I have at work!
Bald_N...what are the chances of a good installation if we takeout the lcd and replaced with a cct board and connect the ribbon to it.
4 channel opto $7:00 and I think I have a DS2408. I would like to have 2 x 4 port optos and a DS2408 (which has 8 channels) we could wire the power boards LED indicators back into the DS2408 as four inputs (5-8) and actually get feedback that the output is actually turned on. Is there a low power opto..i.e. does not take 17ma to turn on the LED. would need to look at this if we want to jump onto the back of the existing 4 LED's.
I assume the board has two power supplies as the relays if all 4 where turned on would be too much for their crappy bridge/zener power supply.
I'll disassemble the powerboard again over the weekend or at work on Monday. There are 3 zeners there so I'm figuring one may be for 5 volt for the timer IC.
If this is the case, then we can use this on the collector side of the optocouplers transistor and the emiter to the relays transistor base pin via a resistor. That way you still won't need to modify the LED side of things and you can reduce the amount of additional components required.
Sorry if I can't explain it clear enough but I'm starting to get a bit tired. I probaly should draw a schematic scan it in and post it.