do I need a rectifier!?

[lennox]

Hi all

after some help chaps, the scenario is...


I'm working in this factory iv been doing some work at and basicaly they've decided they want to come up with a device that shakes glitter on to plants as they go through along the benches.(bare with me hard to explain!!) so the fabricator has mad this gert looking siv that you pour the glitter into and has attached a small motor (12v-15v DC) no other detail was displayed on the packaging for the motor but is literally a tiny thing about two inches long max, looks And this is going to shake the siv with the vibrations.

so IV bought a 12v-15v DC transformer 30w 3a (wanted adjustment to do with the amount of glitter given off) from rs.

i have 12 or 15v dc on the outlet of the transformer but the motor doesn't work? And the motor does work of a 12v battery so the actual motors do work (there are two motors on separate sivs and both don't work)

the motor is defenantly dc and so is the transformer

am I right in thinking that these Mickey Mouse motor aren't working due maybe needing some sort of rectifier? So I get smooth dc voltage? If so can someone point me the right direction of one

hope that makes sense also lol

RS Components

 

[rapparee]

Are you definetly getting 12vdc out of the transformer. Did you test it

 

[lennox]

Yes mate I tested it, 12v dc 100%

 

[Marvo]

How many watts is the motor?

The problem with a voltage as low as 12v is the current requirement will be surprisingly high. Even a 30watt motor could require 3 or 4 Amps running current and considerably higher than that whilst it initially starts. If I were a betting man I'd wager that the transformer is too small and can't supply enough current to start the motor.

 

[lennox]

Literally no wattage info on the packaging of either motor.

im not sure where he got the motor from will have to try and investigate

my only query with what your saying about the transformer being to small is that it starts with a normal square 12v battery like the sort in toys(can't think of the name of them!!)

 

[Marvo]

Even a small 12v battery can give a large current for short time periods. Try putting a paperclip across the terminals for a couple of seconds and you'll see what I mean. (wear gloves and goggles and have a fire extinguisher on standby )

 

[lennox]

So I'll up the transformer then you recon and nothing to do with rectifying the voltage or anything silly like that?

 

[UKMeterman]

First get an ammeter out on a 10 amp setting and see what the peak current is, along with the running current. Also some power supplies are clever and may see the motor as a dead short and refuse to start. Try running the motor on a decent bench power supply..

 

[PEG]

As above,or even easier,measure voltage DURING connection to the motor...I don't need one more thing reducing the amount of glitter in this world...:icon12:

 

[UKMeterman]

Just a little mo, have you connected the sense wires for that power supply correctly?

 

[Lucien Nunes]

nothing to do with rectifying the voltage

A rectifier converts AC to DC. If your power supply unit gives out DC, you do not need a rectifier. In fact, it must contain one itself. Please can you give the RS stock code for this unit so we know what kind it is...

 

[elevate]

There is more info required, such as how many starts per hour - how long will the motor operate, under what loads - start and running currents - motor HP or wattage etc.
If the motor is being used constantly it will probably need a lot more than a power source in the supply circuit.

 

[lennox]

Tony before you began to start shooting people down not everyone is born an electrical genius and I'm 24 years old therefore not got as my experience as all these old boys but that's the reason I'm on here to learn and improve so keep your remarks like that to your self,remarks like that are what keeps people from asking for advice and just bodging it in.

 

[lennox]

But yes tony I have no experience in designing industrial custom equipment for factory's no, never had to help in design a bloody automatic glitter shaker lol there's so many variables that need to be factored in,let alone not be given any info on this motor which may need changing of the motor isn't powerfull enough

youve got a bench passing along via one motor at a certain speed under a custom frame which needs to siv an extract amout of glitter (due to requirements from tescos etc) so there are a lot of variables and its a lot of trial and error!!!

 

[telectrix]

i think you'll find that the power supply ( transformer/rectifier ) that you have is simply not man enough for the motor.

 

[lennox]

Thanks for all the positive comments, clearly underestimated the amperage of the motor, being such a small motor (surprisingly powerful for such a small thing lol)

Bought bigger supply from Maplins and now in business,now the glittering shall begin lol!

 

[Marvo]

Glad you got it sorted out. I'd be interested to see a picture or two of this thing in action if you're up for attaching a couple. I've seen some things in my time but never a glittering machine

 

[lennox]

Yes I'll get some up Tomo once it's all in place! Cheers

 

[UKMeterman]

I would still say measure the current of the motor, a bench power supply from Maplin is unlikly to be rated for full load hours at a time.

 

[lennox]

Ukmeterman once iv got the pictures up it will be easier to explain, the siv can only hold x amount of glitter and will only be Running for the duration it takes to empty the siv over one bench full of plants(due to the setup you've got to push the bench into plane,the bench then motors towards the glitter siv and then pushed away)Then will be turned offf,the bench with the pretty glittered plants will be pushed to the new position and a new bench wil be put in its place and the cycle will begin. So at a guess will be 10 minutes between glittering and glittering will take about 1 or two minutes. Difficuilt to explain might even draw a picture of the set up for you guys also!