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?
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.
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
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.
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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
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