Cheap DAC for PC

DAC - Audio coming out of a PC has the advantage that the Audio DAC hardware is tightly coupled to the PC hardware, which may include DMA (direct memory access) and IRQ (Interupt Request Controller).

For a DAC external to the PC - the external hardware with DAC is mostly likely not "tightly coupled" to the PC hardware AND Windows programming and Windows messaging may add delays.

If you must use a external DAC then perhaps a USB 2.0 High Speed device (480MBps) may be required , which sould also include the USB windows drivers and arb gen software.

An alternaive is to buffer the arb waveform over the external interface and then the external device "plays back" the arb wave form.

Joe

On a sunny day (Sun, 15 Mar 2009 10:02:26 +1100) it happened "Joe G \\(Home\\)" wrote in :

Or find the DAC output on the soundcard and bridge the coupling cap?

Some sound cards have been designed in to the motherboard... so coupling cap may be a little hard to find.

Joe

These: have the TI PCM2902 chip: . It should be pretty easy to tap off the outputs and shift the DC level to where you want.

Clifford Heath.

We have used these with good results down to DC, for laser beam positioning, and several dozen people have copied the project.

You will need to add a level shifter as the output is centered around

This is generated using a laser scanner controlled by the above unit, there are some artifacts in the video caused by the cell phone camera. Please also keep in mind that these are galvo scanners, and thus are only capable of about dc to 3 khz response with the mirrors attached.

Steve

The missing link:

Steve

These do look very good for the price. But the Behringer specs say the lower limit is 10Hz and I need 2 or 3. Would a conversion be necessary, or relatively easy without a circuit diagram? If so, how should I approach it?

The main point of my OP was that I needed to output subaudio from the PC waveform generator.

Neville Kingston

You remove or jumper over the output coupling caps, which is easy. You then may need a level shifter, which is 1 opamp and a few resistors and one potentiometer for setting the amount of shift.

Steve

bypass the decoupling caps of the soundcard.