Hello
Recently I have been experimenting with one of my hobby project to control a relay with some Micro Controller and that part is been taken care of.
which does exactly what I am trying to acheive. Though my question is as per the relay above I need to change the resistors connected to the Darlington array , if Some one could explain to me the math behind it as to what we are trying to acheive and how it will work and what i sthe principle behind it. Please donot repond to this question if you dont know exactly what you are talking about and I dont want suggestion like , Well you can use some other Hbridge Driver or Blah Blah Blah .
and I am using ULN28003 and not ULN2003 , I believe the difference between these 2 is the number of outputs plus some perating voltages
Bluroom look at the PDF link I posted its the same symantic but driving the relay that I posted the link RT314A12
Thiis relay has following specs
* Contact Current Rating (Amps.) = 16
* Coil Resistance (Ω) = 360
* Coil Power, Nominal (mW) = 400
* Actuating System = DC
* Coil Power, Nominal (W) = 0.40
* Input Voltage (VDC) = 12
* Dielectric Strength - Coil Contacts (V rms) = 5000
* Tracking Resistance of Relay Base = PTI250
* Coil Rating = Sensitive
What i was asking what needs to be changed in the posted PDF symantec to drive this Bistable relay??
Ah it's latching opps. The resistors are the + path for each side of the coil, drop a resistor on your relay 4.7 to 47 may be fine. It's a really inefficient design as the 2803 will also have to drive current through the resistor too.
Its not a contest nor a school project i am way too old for that.lol
I am an engineer (software) and its a design that we are pitching .. you can check my company @ **broken link removed** and I am Zeeshan you can check my profile there under about->management.
I can further discuss this with you but not in a public forum. If you feel like drop me an email @ zeeshan.taj@gmail.com.
We are using Atmega168 along with this darlington driver to drive relay. There is a whole concept behind this.. All communication with avr is radio based.
So here is the design--- Radio Transciever --- AVR ---- Darlington driver...
Would you mind telling me the logic behind using resistors to drive this Bistable relay and when we are connection both sides of the coil to +(positive) and when opening drain on either end lacting the relay.. I know its all about Current flow through the coil but I really want to know the Math behind it. I mean the calculations of resistor to acheive this HBridge sort of operation.
It's a kludge, the 2803 can only pull down to GND. You need a positive voltage on the other side of the relay and the 2803 can't do that so that's what the resistors are for.
The correct value will depend on the relays minimum pull in voltage. Try 47ohms first and see if the relay pulls in, if not decrease to 33ohms etc...
Try reading the datasheet. It's a simple 1A to 3A dual half bridge, that and 4 diodes can run your relay no problem. Just hook it up like the robot room link I sent you.
Its really very simple and elegent I love the simplicity.
though I have 4 Relays to operate minimum 1 and max 4 .. independently.. do you think they have another version with more output lines??
Ok Boncuk and blueroom I made the symantic to show you my connections and as per Blueroom I reduced the resistors step by step to nearly 20 ohms and the relay would not respond. the Only way I made it to latch was directly applying power to it from the adaptor.
Boncuk I remeber you have solved this problem before , and I cant seem to remember which forum was it , this was the exact problem and you gave some suggestion which eventually solved the issue. Please look at the symatic and let me know what I am doing wrong . I have included all the related data in this JPG file. Thanks in advance