Hello @ALL Well here i am i was reading thru the forums after stumbling across some of the cool PC mods then i noticed the electronics forum so what the hell i got no 1 else i can ask about this kind of stuff so here goes i have a problem in that i want to control a 12v motor forward / backwards http://www.maplin.co.uk/Search.aspx?criteria=N04BQ&doy=4m7&source=15 i understand that i must reverse the polarity on the motor to achieve the forward / backwards motion that i require so i purchased this 12v DTPT Relay http://www.maplin.co.uk/Search.aspx?criteria=FJ43W &doy=4m7&source=15 what my problem is, is that Maplins dont have ANY Pinouts for this Relay ive searched the internet for some datasheets to no avail i would ideally like to wire the relay up to 1 of these kits so i can Remotely switch the Forward / Reverse Action of the motor http://www.electronic-kits-and-projects.com/3142.htm ? i am running it at the moment via a Standard rocker switch using the plan from here http://www.distel.co.uk/MOT_CON_F1.gif to control the Polarity i would like to know how to connect it all together so i can have a Manual Switch Controlling the Motor And also the *IR Relay Board* / DTDP relay when needed Do i the correct type Relay for i want to do ???? Can any one out there with experience of these things please lend a hand as this is really got me Stumped any drawings *rough schematics* / any input would be Greatly Appreciated please can anyone give me some insight on how to achieve what i want to do Thanks!.............
Maplin's paper catalogue has far more info in it than the website. For those relays, the two pins on their own at one end are the coil. Of the 2 rows of 3 pins at the other end, middle ones are commons for each pole, outer ones are the switched, with 'normally open' near the end. Code: o o o o NO Com NC Coil o o o o This one's just the same layout, it's standard.
WOW Thanks m8 that was FAST i only just posted!..... now all i need is the info to wire it all together ...... do i connect the 12v + | - to the coil then connect up relay in X style then do the middle com pins go off to motor if so how does it Switch what triggers it? where would i put the IR Relay Board would this act as a Trigger ??? im lost
You didn't make this clear in your first post, but do you simply want to change which direction the motor turns or do you also want to turn it off? If you want to turn it off, you'll need to use another switch to do so, as the relay will only have two states, either Com and NC are connected or Com and NO are connected. Now, as for your second post... Yes, simply connect +12v and ground to the coil contacts. For safety, place a small diode such that it is parallel the coil but opposite in polarity, like so: Code: X - - - - - +12v R | e - l ^ a - y | X - - - - - GND To control the direction, put the motor contacts on the Com pins. Connect to voltage source to either the NO or NC pins, and then switch them for the other, like so: Code: +12v - - - - - 1 3 5 N C N o O m C GND- - - - - - 2 4 6 Conenct the positive motor terminal to 3, the negative terminal to 4, then connect 1 to 6 and 2 to 5. Would've shown this, but it would've made the ASCII art really big. Note that in this setup, the motor will normally run backwards unless voltage is supplied to the coil. To get the opposite effect, just change 3 and 4. The tricky part is getting both IR and mechnical control of the motor without the two stepping on each other. I can't quite think of how to do this, but I'm sure someone can.
Some pictures here. Similar to whypick1's, they've just swapped in & out ends. Fig.1 is like the relay connections.
A note about figure 2 in the link that cpemma provided: During switch over, if connection DE is made before BC is broken (or AB made before EF is open) you short your power supply. It will just be momentarily, but it can be hard on the contacts and reduce their lifetime. That risk is easy to eliminate by switching the role of motor and power supply. Polarity on the motor is still reversed, but if the motor is shorted there is only a very limited amount of energy available to burn your contacts. To further reduce wear on the contacts you can put a varistor or a similar device across the motor leads to limit the inductive voltage spike when the motor is turned off.
It's an extremely low risk and would IMO only happen if a pair of contacts got welded together through wrong choice of relay, too low a current rating. They're relatively slow devices with a few mS dead time when the contacts are changing over, and both 'common' contacts are attached to the same moving armature so will break together. A fuse would take care of serious faults. What's potentially a bigger problem is suddenly switching a motor going one way into reverse. Some of the robotics sites may help, but they usually go for solid-state (H-Bridge) switching.
