Review: Voltage Blaster

27th November 2021

 

Today's review I am looking at the Voltage Blaster, a hardware collaboration project from Phil of Phil's Computer Lab and Necroware.

 

The Voltage Blaster arrived yesterday -
I paid around £12 for it ready-made

The Voltage Blaster is an 8-bit ISA card with one simple purpose - to provide minus 5 volts to the ISA bus. The reason this is necessary is because many modern ATX power supplies fail to provide this voltage rail to the motherboard that older AT power supplies used to, and many sound cards require -5V to operate correctly.

If you are powering your old retro PC with a modern PSU, and possibly using an ATX-to-AT converter to get the old P8 and P9 connectors your motherboard needs, it is highly likely you need this!

For my test I used my original ZETA P-10 XT motherboard, and tested the bus first to confirm there is no -5V. With the old P8 and P9 connectors it was easy to spot if the PSU was providing -5V because of the presence of a white wire on P9. With an ATX power supply or using a AT-to-ATX con verter, it is common to not have this present. A simple test exists: all ISA expansion slots take in a -5V signal from the motherboard at pin 5, so a quick multimeter test on that pin on any ISA slot with the machine powered on will easily tell you if the -5V is present. If not, the use of a Voltage Blaster is required.

The Voltage Blaster is a simple inverter, taking power from the +12V line, inverting it to -12V and reducing the voltage output to -5V. Any expansion slot can be used for the Voltage Blaster card.