18 replies to this topic

[Rollerfreak987]

Hello!
I am in need of an adaptor for the K'nex 12 volt electric motor. I am willing to pay within 10-15 dollars for it. Just the adaptor, if anybody decides to sell me their motor too, I will probably go 20-30 dollars. The best way to purchase would be through eBay, just make a simple Buy It Now listing, and I'll pounce on it before anybody else. If you're interested, leave a comment. United States members only, please!

Thanks.

[Zorn]

I'm sure you can go to an electronic's store somewhere local and pick up a 12 volt adapter for less then $10. I know I've purchased a few adapters for the rippin' rocket boosters for $5-6 each. Several of my adapters that I use for my grey motor's aren't the original ones either. However if you're looking for a whole motor then disregard this message.

[Rollerfreak987]

i have some other non-K'nex adaptors, but they spin at different revolutions than the standard K'nex 12v adaptors.

[Maxlaam]

Bullshit. Sorry for my words but 12v is 12v. The only thing you need to worry about is that it is rated at atleast 300mA. Neither influences the rpm though. If you have a universal adapter you can select the voltage and change the speed it runs at. Which is highly reccomended because of it's versatility. You don't need the knex adapters.

[Rollerfreak987]

But they don't work when I plug it in, then it gets jammed up.

[Zorn]

What jams up? Are you sure your adapters are 12V? Max is completely right that it shouldn't change your rpm. The K'nex adapters are 500mA. So if you get an adapter that's 12V, 500mA you will be golden.

[pkiknex25]

Ben and I have noticed a difference between using different 12V adaptors also. We didn't look at the ampage, but there was a difference between Knex adaptors and non-Knex adaptors. We checked and tested them too. Switched motors, same power supply, and we found it was definitely a difference in the adaptors. (but again, we didn't look at the amps)

[Rollerfreak987]

^ I tried that too!

And roller coaster kid: I will check tomorrow afternoon to see what they're. And they will just slow down really fast then stop. Then the worm drive will fall out on the bottom motor, and I have to put it back in. They're probably not 500mA.

[Zorn]

My guess is that they are lower then 500mA then. Amp's are essentially how much power the motor has in this case (So max is right that it will work with 300mA, but it will slow down quicker under a load.) Where Volts will determine the RPM. I don't know whats happening to the worm drive though. I've never had one of those come off.

It really shouldn't change anything having different adapters though. I put away my adapters for Tundra today. One was a K'nex one and the other was a different company. I never noticed any difference in the two. They are both 12V 500mA.

[Rollerfreak987]

Oh, well I found a 500mA adaptor but it's DC, I was going to hook it up this morning but I ran out of time. I don't think it will work because its DC. I'll find out later.

^You also had single motors on Tundra, I'm using 2 per rod on Centaur, 2 motors doubled up on each other. I have 4 in all, it's just 3 are the same revolution and the 4th is just different, that's why it's not working.

[Maxlaam]

Nope, K'NEX motors are Direct Current Motors, DC. Not Alternating Current. If you put AC on it, they won't do anything.

The only thing that I can think of is that A your adapter is broken or B you are experiencing a huge voltage drop between your adapter and your motor.

If your worm drive is coming of it means you are putting too much strain on a single motor. And they should never come off if you let it spin in the right direction. If you spin it the other way it will push itself onto the shaft instead of trying to come off. Using a universal adapter really helps with this as you can often switch the direction of the current.

Edited by Maxlaam, 28 January 2013 - 06:50 AM.

[Rollerfreak987]

Ok cool, so it may work. I'm sure it's not broken, and maybe, I dont really know I'm not good with electronics and items like that.

Also, if the number on it is 300mA will it have a slower rev than a 500mA motor?

[ForgotToGrowUp]

I suggest going with something like this. I have 2 of them and it has worked out great. Easily power 4 motors with one power supply.

http://www.sscoaster...c-motors-14406/

[Rollerfreak987]

Alright. I got all 4 working with that adaptor I found. Thanks for the help.

[Schokotod]

So I know I'm reviving a dead thread, but I have had a lot of trouble sourcing an adequate off brand adapter so I thought I would post my findings.

 

All my understanding, and what everybody has told me, is that as long as the AC to DC adapter has an output of 12V DC and is rated for at least 500mA it will work identically to the original K'nex adapter. 

 

So I bought a 5 pack of 12V DC 1A adapters from amazon

 

Link: https://www.amazon.c.../dp/B00FEOB4EI/

 

They worked, but not like I wanted. The motors spun in the wrong direction, which was fine, but they also spun at only half the speed (roughly) of the official K'nex adapter. I tried all 5 of them, and they behaved the same way, so I am sure it's not just a bad adapter.

 

Next I thought "Hey. these are 1A. Maybe a 500mA one will act better?" Now according to what I know, there should be no functional difference between the 1A and the 500mA ones for K'nex motor, but I tried it anyway.

 

So next I bought this 12V DC 500mA adapter.

 

Link: https://www.amazon.c.../dp/B002IS47D8/

 

And it does the same thing as the 1A adapters. Granted I didn't test them side by side. Regardless, neither of them compared to the original K'nex adapter. They spun at half the speed and in the opposite direction.

 

So I got really frustrated, but then I decided to actually do some science on this.

 

HERE IS WHAT I FOUND.

 

The experimental procedure was taking the multimeter and inserting the positive (Red) lead into the tip and touching the black (Negative) lead onto the sleeve of both the 12V 500mA on brand adapter, and the 12V 500mA off brand adapter.

 

The multimeter read +12.38V for the off brand adapter and -18.20V for the on brand adapter. (!)

 

This tells me two things.

 

1. That if you want an adapter for a K'nex motor that works the same as the original, make sure the tip is negative and the sleeve is positive. It WILL WORK with the opposite polarity, but will spin in the opposite direction.

 

2. If you want an adapter that is as powerful as the original one, it needs to be 18V and not 12V. A 12V adapter WILL WORK, but it will be significantly less powerful than an official adapter.

 

(Disclaimer: I am not an expert, I can be wrong, and using to high a voltage can damage your stuff, so I take no liability for you trying a 18V motor and burning your stuff.)

 

I'm kind of frustrated I didn't test this earlier, but live and learn. Next I am going to order an 18V adapter (Making sure I get a negative inner tip) and will see how that goes.

 

Also, what the heck K'nex? Is it just that my "12V" adapter is broken, or do they usually give out 18V? If so, just label it as 18V and save us the trouble.

Edited by Schokotod, 10 January 2017 - 02:34 PM.

[YolosweggLord]

Funny thing, I brought 5000+ pieces from a community sale in Apopka, FL less than a month ago. Included in the haul was an almost complete HTT set, missing the 12V motor and some minifigures- but the adapter was there.

Edited by YolosweggLord, 10 January 2017 - 01:12 PM.

[Rollerfreak987]

Laughing at this thread because I have like 10-11 adaptors now, and I was in Apopka, FL a little while ago.

I have noticed the same thing in that some of my motors work together and some don't. I have 9 12 volt motors right now and there's certain combinations of motors that won't work with each other. Maybe that has something to do with it, but I'm not sure.

[Schokotod]

Funny thing, I brought 5000+ pieces from a community sale in Apopka, FL less than a month ago. Included in the haul was an almost complete HTT set, missing the 12V motor and some minifigures- but the adapter was there.

 

I'm wondering, what voltage do other people's official K'nex adapters output? If I find that most people have ones that output 18V I will buy 18V adapters and not 12V so I get extra power without worrying about burning out the motor. There is a huge difference between my off brand 12V adapter and the official one.

So what voltage does your adapter ACTUALLY output? (Not what it says on the cover. Measure it with a multimeter.)

 

If we can figure out what voltage is safe for long term running, we can get a significant power boost to our motors, which I am sure people would love.

[YolosweggLord]

Laughing at this thread because I have like 10-11 adaptors now, and I was in Apopka, FL a little while ago.

I have noticed the same thing in that some of my motors work together and some don't. I have 9 12 volt motors right now and there's certain combinations of motors that won't work with each other. Maybe that has something to do with it, but I'm not sure.

Coincidence? I think not.