usbasp to suppose voltage for experiments?

[casper.bang]

Unlike high quality programmers like the AVRISP mkII programmer, on cheap Chinese USBASP clones*, I guess there are NO protection what-so-ever against shorts between the 5V power rail and group - so using it to do anything else than power programming (say run experiments on a breadboard) is thus a bad idea as it puts the USB port in jeopardy.

What would the easiest way be to add some protection? I'd like to make a programming adaptor (10 pin header) which can also power the board during breadboarding. Is a small linear 3.3V regulator the way to go then?

* http://www.ebay.co.uk/itm/10-Pin-Cable-USBASP-USBISP-AVR-Programmer-Adapter-USB-ATMEGA8-ATMEGA128-Arduino-/381216028308?pt=LH_DefaultDomain_0&hash=item58c23ef694

[Psi]

Shorting the 5V USB rail to GND isn't an issue. The USB standard requires protection from shorts be incorporated into the USB port.

However, shorting USB power to a higher voltage might be a different story, never tried it.

[JohnnyBerg]

Isn't there a 3.3V regulator on the programmer?
The listing says it can deliver 3.3V

[casper.bang]

Isn't there a 3.3V regulator on the programmer?
The listing says it can deliver 3.3V

Indeed, on the rear side there's an AMS1117 [http://www.advanced-monolithic.com/pdf/ds1117.pdf] which I guess means I am safe.

[casper.bang]

Shorting the 5V USB rail to GND isn't an issue. The USB standard requires protection from shorts be incorporated into the USB port.

However, shorting USB power to a higher voltage might be a different story, never tried it.

So what you are saying is, attaching the programmer directly to a breadboard should be safe as long as it's the only power being used? I do wonder then why you never really see USB programmers+prototyping boards in one.

[Grapsus]

For low-speed (1.5 Mbps, which is the case for USBasp) and full-speed (12 MBps) you have relatively cheap isolators :

http://www.amazon.com/HifimeDIY-Isolator-ADUM4160-signal-isolation/dp/B00F4SCCR2
https://www.olimex.com/Products/USB-Modules/USB-ISO/

They have full galvanic or optic isolation for both power and data lines so it should protect your computer in case something goes wrong.