Trying to find right transistors to use for a project with DAQ board and DIO ports... sal2

[sal2]

Greetings, All

I would like to switch on and off 4 of my 4mW pen lasers on and off (in various ways)
using my usb 6008 DAQ device
however I don't have enough current/voltage to power my 4mW pen lasers from my
usb-6008 DAQ device. Here are some Specs that I've measured from my device.
The digital outputs on the DAQ device produce:
5V, and 1mA (they have a 4.7k ohm resistor I can't get to inside)

What I would like to do is connect my 4 digital outputs from my DAQ device to
4 transistors that would switch the power on and off from a 5V dc Power supply.

I'm having issues trying to figure out which Transistors I need. Can anyone give
a little assistance.

Also if you have any other suggestions I'm open to that also. I'm allways
willing to learn something new.



Thanks
sal2

[LYu]

Hi sal2,

Consider the following suggestion:

How Can I Increase the Amount of Current My DAQ Board Can Source or Sink through the Digital Lines?

Thanks,
Lesley Y.

[Buechsenschuetz]

I would recommend a PhotoMOS opto-coupler relay, such as the AQV212 from Matsushita. The input of the relay just needs 1.2V at around 3 to 5 ma. The output has very low impendance (not more than a few tenth of an ohm) and can handle around 250mA and 25V.

When using transistors or transistor arrays (such as the ULN2003), or an open-collector driver like the 74x07 you always have some voltage loss due to saturation voltage of the output transistors. The PhotoMOS relays have an almost ideal low-ohmic outputs with no saturation voltage. We use the AQV212 to switch the supply voltage for a 15mV laser.