Switch a 12v circuit with a 5v circuit

[cc005340]

Hi All,

Sorry about this but i am more a computer programmer and therefore dont know so much with electronics, however here is my question i have a velleman experiment board K8055N (**broken link removed**) which has digital output at 5v, what i am trying to do is from this digital output i want to switch on a 12v component, however of course there is not enough voltage from the USB board to power the component, how would i go about solving this issue?

Thanks very much for your responses!

Scott

 

[ericgibbs]

hi,
What is the 12V component.?
E

EDIT:
Do you need help identifying the component.?

 

[Reloadron]

This is what you have:
Specifications

• 5 digital inputs (0= ground, 1= open) (on board test buttons provided)
• 2 analog inputs with attenuation and amplification option (internal test +5V provided)
• 8 digital open collector output switches (max. 50V/100mA) (on board LED indication)
• 2 analog outputs:
  • 0 to 5V, output resistance 1K5
  • PWM 0 to 100% open collector outputs max 100mA / 40V (on board LED indication)
• general conversion time: 20ms per command
• power supply through USB: approx. 70mA
• dimensions: 5.7 x 3 x 0.8"

So per Eric's question the requirments of your 12 volt components or devices need to be known. What you have gets you up to about 100 mA and I would remain below that. So if your component requires more than about 100 mA (more like 80 mA) then more effort is needed like adding a relay or driving transistor. It will always go back to what your component is.

Ron

 

[cc005340]

Hi Guys, Thank you both for this details, my component is an electromagnet **broken link removed**

I have seen this post (http://forum.velleman.eu/viewtopic.php?f=3&t=4057) and it seems that i can add in an extra power supply to the experiment board and use the clamp pin

 

[ericgibbs]

hi,
Extract: Magnet spec.
Input Voltage: 12V DC
Current: 0.33A

The link advice looks OK.
The ULN is rated at 500mA/pin , use the clamp pin as stated.

E

 

[cc005340]

Hi Eric,

Thank you for your comment, just a little concerned that the output is stated as (50V/100mA) is that a max of 100mA as the electromagnet runs at 0.33A which is 330mA of course

What's your thoughts?

Scott

 

[ericgibbs]

Hi,
As the Velleman guy says in your link to that forum, the 100mA is VERY conservative, if you use only one output from the ULN.
Its stated as 100mA in case you used all the output pins at say 100mA, you could exceed the ULN power dissipation.
E

 

[cc005340]

Eric, you're a star thank you for this detail, i will try this out soon and update the forum post on the result. Just to be clear i should be able to just run just the one component at 0.33A on one output pin as long as i dont add any more components? Thank you

 

[ericgibbs]

Eric, you're a star thank you for this detail, i will try this out soon and update the forum post on the result. Just to be clear i should be able to just run just the one component at 0.33A on one output pin as long as i dont add any more components? Thank you

hi,
Yes.
I have a K8055, which I have modified and reprogrammed to use a 18F2550.
Checking it visually I see that the ULN is OK for 330mA, but be SURE to connect the PCB clamp pin to +12V ,as per the other forum link.
E