USB function generators?

USB isolators are probably not expensive.

In this case it would be a bit more challenging because the thing is also supplied via the USB jack. I could fix that, but ideally I'd like something I can plug in and it just works.

We bought a few of the Keterex boxes. They work well.

Cheers

That could work, if it's happy with 400mA. Unfortunately a lot of stuff these days exceeds even the max load of 500mA, in particular disk drives.

I couldn?t say if it actually sources 400ma since our USB devices have their own power source.

On another note, My laptop's USB port cannot supply power to 2 2.5" drives at once, nasty head movement occurs.

Cheers

I think that's what the Keterex datasheet says.

Well, that's the other problem. I've usually already got some lab stuff hanging on the laptop and while this is a ruggedized computer there will be a limit. The Velleman datasheet isn't exactly forthcoming with data like that.

Analog devices have a USB isolator IC, but you still need power isolation.

Joe

That?s what is in the Keterex box.

Cheers

USB is always a driver hassle. I try to buy USB devices that also work in Linux, so if the company goes bust, you can at least run the box under linux.

$300 would get you a nice function generator at a ham swap meet. My PM5191 was $125 in a freakin' store (RA Surplus, now defunct) years ago. You can't get much money for low bandwidth generators these days.

Well... a good HP3314A still sells for a couple of hundred. More recent Agilent generators fetch even more. AFAIK those are USB and/or ethernet controllable.

If its from Velleman I'd stay away from it. They also sell kits. You can download the schematics from their website. The designs are far from brilliant and kits that are intended to be connected to the mains only meet the PCB design rules minimum clearance.

Yes, it is from Velleman.

ss

The HP3314A has a control panel, so it's not like you are buying a black box USB device from a Chinese company that won't exist in a few years. Black boxes can become bricks if the drivers are history. Think about all the ISA controlled items that have become bricks. ISA GPIB boards are valueable only for their trade in value with Nation Instruments. Anybody need a scsi drive? Now ethernet is another story. It doesn't need drivers.

I've seen the similar Fluke or Tek function generator that cuts out at

Indeed, the USB isolator and a self powered USB hub would be quite nasty.

Perhaps a miniature laptop with big batteries could be floated with the test equipment, but the stray capacitances could cause problems.

Doing measurements with the test system floating on the mains voltage would also be dangerous.

Another challenge in many of my jobs is the EMI that some of these converters kick out.

In that respect I am quite brazen but I make sure nobody gets too close to my lab bench while this stuff is running :-)

How do drivers become history? With all my black boxes they came with the box. Ok, I do not change operating systems at every whim some guys in Redmond might publish. If a "new and improved" OS is not backwards compatible with my legacy stuff I won't buy, I'll stay with the old OS.

Huh? You can buy plenty of brand new PCs with numerous ISA slots. Regular quality or industrial stuff. And I'd venture to say that you will find a similar selection 10 years from now.

Yup, out here there's abosultely nothing going on of what you have in the Bay Area in terms of electronics stores. IOW, out here there are none left.

Not using potted or toroidal coils in the buck area usually causes this and a few bypassers here and there.

Nice EMI radiator using open coils :)

It's raining here, headed slowly your way.

Got leaks?

Rain in May is unusual here. We had a very wet winter, lots of snowpack, long hot (indoor) showers in the forecast. I hope it's a trend.

John

Potted or "shielded" inductors have a surprisingly large air gap, camouflaged by using a potting compound in "ferrite color". A guy from the German NG recently did a test. Soldered an LED to an inductor of same type, held it over the other ... and there was light :-)