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Questions about relays Answered

I am building a robot with a specific purpose and I have hit a snag. My remote controls on the receiver end are 4.5v and the motors I want to run are 12v all of it is DC. The relays I have don't pull in a 4.5v so I need another way to doing this. I either need another way of pulling in the relays; I need relays that pull in at 4.5, or some other intelligent solution that I cannot think of. Please help!



. I'd go with 4½V relays. Make sure they will handle the current of starting the motors.

. Maybe. "Contact rating: 30VDC 1A." How much current does your motor pull?

Well the funny thing is i'm using the little rely to pull in a bigger relay 9v to 12v. I’m a noob for sure but I know that the relays I have will work with my motors because I have tested that part. The relays I have are standard in most Nissans. There is probably a better way of doing this but until I figure it out, I just want to make it work.

if you describe better what you are doing (maybe with images) we may help more

ok will do but i need a day or so to get that stuff together, thanks a bunch guys

ok I have a 4.5v bat I need it to switch a relay to run a 12v circuit.

my components are

1 - 4.5v 600mAh Battery (runs my RF controls)

several - Relays http://www.goldmine-elec-products.com/prodinfo.asp?number=G16523&variation=

2 - 12v motors (no other information)

1 - 12v (13.6v) 1.4A Battery to run my motors

My major problem is that my relays pull in around 6-9v

I have ordered some 4.5v relays to be intermittent between the 4.5v batt and the other relays, this should fix my problem but its not ‘smooth’ I am also starting to build my own small circuit boards so if you guys know a way I can make this work well let me know and I’ll do it.

I order parts from here:

I am making some drawings for you guys to look at as well.

Thanks a bunch for the help!

your plan (4.5 V relays - 12 V relays - motors) is ok and can work you can use 5 - 6 V relays instead of 4.5 V if they have good enough current rating then you can skip the 12 V relays and control the 12 V of the motors directly with the 1st relays solutions with transistors instead of relays are possible too. but it can be left for later if the motors are from power tools then i think they take like 5 - 10 A each

what you have now can be made with 2 relays and not 4 now add the 4.5 V relays to the existing stuff you can use the car battery instead of the second battery if the omron 8567 relays are 12 V. you can use it if the relays are lower voltage too if you add resistors the 4.5 V relays can be replaced with transistors. its more compact and the batteries in the 4.5 V device live way longer


I have these controls


On the receiver end each channel has 2 negatives and one positive so you can switch polarity. My transmitter is not doing anything on any channel and I get constant current flow in one direction even when the transmitters off. I don’t know much about these types of controls and I looked through the manual and can’t find anything to help. Is there something wrong with the controls or is something else going on? Know anything about this stuff?

connect led (with resistor) to the output of the module instead of everything else if it works with leds your relays were too high load for the module if it does not then the leds are too low load (add 47 ohm 1/2 W resistor in parallel) or your module is bad

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. It won't be very elegant, but it will work for proof-of-concept purposes. Just make sure the coil of the bigger relay doesn't pull more than an amp.
. Don't forget to install clamping diodes.
. You should be able to drive a transistor (or other electronic switch) with the control output and have the transistor drive the bigger relay.

im sure a 5 V / 6 V relay works ok on 4.5 V if you can open your 12 V relays maybe you can weaken the spring to the extent where it works on 4.5 V. i'd not recommend this cause relays with weak spring are less reliable (may open / close just from fast movement of the device they are in)

They are in a solid plastic case but I’m not opposed to the idea. Right now I’m just trying to get a prototype running to test my overall concept. Thanks a bunch both of you for posting, I am checking this frequently!

not sure if this has been answered yet, I don't feel like reading all the other posts cause I'm tired and going to bed. This link might be very helpful, it also finally got me to understand how to use transistors:


basically do figure 2 with a relay as a load and a clamping diode in parallel with the load (if you don't know what that is, it's pretty much any diode that's "backwards" like a 1n4001, 1n4002, 1n4003 .... or something like a 1n4148. Those are just some common diodes off the top of my head.)