DPDT Relay - DC motor control: Forwards/Reverse

[slimplynth]

Hello all...I've had some DPDT relays in my box for ages and now have a use for them - just need some help please.

the relays are these... http://81.134.141.187/epages/Store.storefront/?ObjectPath=/Shops/Store.TechSupplies/Products/REL002

I got a data sheet from here, diagram in attached image.

The trouble Im having is using them as per the drawing below.

The attached Image1 would make this easier if the pins were labelled. (I've googled myself for KL2P-F to no avail - there are plenty of relays which I can find pinouts for but not this one and I'll be gutted if my guessing goofs it up)

Cheers

edit: My guess was that the terminals at the end (and in line with the notch) are the NC terminals shown above

 

[hippy]

The circuit looks okay to me but I'm no expert on transistors. You can check the relay pinout with a resistance / continuity meter, determine which are the coil and N/C contacts, apply voltage to the coil and find the N/O contacts ( which will have closed ), from that determine which are the common points of the switches and which switch is which.

 

[wapo54001]

Don't forget the diode around the relay coil.

You're using these two transistors as switches. Why not use FETs instead?

Don't you want to use pulldown resistors on the bases/gates to insure proper operation?

Depending upon the power requirement vs contact specs, you might want to introduce a delay to allow the relay to settle before applying power across the contacts. Easily done with a picaxe

 

[Andrew Cowan]

The circuit looks good (plus the diode as wapo points out - pointy end to +V).

You shouldn't need pulldown resistors on the transistors, as PICAXE outputs are totem-pole outputs (+V,0V).

A

 

[syntony]

I prefer OPTO Coupler than transistor

working good with PICAXE, good insulation between circuits

 

[slimplynth]

Cheers Hippy, might test this on an 08M first, to be on the safe side.

Andrew/Wapo: sorry for not making it clear - I found the diagram on the wesite below.

http://www.me.umn.edu/courses/me2011/robot/technotes/bidirectional/bidirMotor.html

 

[wapo54001]

I used relays to operate an electric trim motor on my experimental airplane. Because I wanted maximum safety, I used a design that holds both sides of the motor at ground when not in actual use. Then, when I want to trim one way or the other, I activate one of the two relays to connect that side of the motor to +12.

The "motor" is actually a linear actuator with in-built limit switches, and this factor also played into the design.

Just a thought, but you might consider two relays and remove the power transistor from your design.

 

[Taniwha]

edit: My guess was that the terminals at the end (and in line with the notch) are the NC terminals shown above

Looks right, but would be easy to identify with a meter.

 

[hippy]

Just followed the link and that seems to be a 6V coil; so why power from 12V ?

Also you don't say what actual problem you are having we can help with.

 

[slimplynth]

Hi Hippy, no i'm not using 12V. Have got 4x 1.2V AA's... I wondered if the 6V coil would be an issue but while I was testing, as you said to, it seemed to be ok.

Is there a problem with the power supply I've been/planned using?

The original problem was just wanting to know how to use two DPDT relays to control a rover backwards and forwards (independantly); having read up on H Bridges, then stumbling after looking at the data sheet for the relay I'm using (against the circuit diagram above) - I caved in and asked for help.

Thanks for your suggestion to do the testing, which with the gift of hindsight now seems obvious.

Had to pack it all away for dinner and an inquisitive 3yr old; who wanted to know what every single item on the work top was called and if it would stretch . Will hopefully get it done tomorrow.

Cheers

 

[slimplynth]

Evenin' all

Cheers for helping with the relay, bot will now have backwards & forwards. (had a few days off work recently to get a little further to the blimp)

just need to add the contents of the centre breadboard to it...

obviously not the entire breadboard to be carried by the blimp (or the relays) - the bot is just the ground support (need to imagine it's missing srf01 head)

 

[BeanieBots]

Cute looking trike!
Good idea to try things out on a land based vehical before moving on to the blimp. Far less to worry about but the principles are the same so all you learn on the ground can be transferred later.