[Smertrios]

I ran into a problem today when testing my new geckodrive 320's and servo motors when I found out my laptops parallel port is using 3.5v and geckodrive 320's are made to run with 5v. Since I can't tell just by looking what/if a breakout board is going to do any level shifting for me I'm stuck =>... be nice if there is a relatively cheap circuit I can craft to accomplish this even if its on a breadboard.

My rather limited electronics knowledge is telling me I may be able to use a regulated voltage source and 555 timers but there must be a better solution. Maybe an opto that can run on 3.5-5v so it would work with both 3.5v and 5v computer parallel ports.

Just had a thought... isn't there a parallel port plug available somewhere that does this using a wall power supply? So I put this plug on my computer than my cable into the plug and voila 5v logic?

[phantomcow2]

Yep, check out basically everything at cnc4pc.com

The breakout boards there take an external 5v supply, and will make all signals 5

[erase42]

i didnt really think about it at the time, but i saw a usb to parallel adapter at wall mart the other day when i went to get a usb to serial adapter to run my machine. I know the voltage at the usb port is 5 volts so its completely possible that it may work for you.

[Smertrios]

erase43 - I did a search for these adapters at www.tigerdirect.com they are not very expensive but a search for "usb parallel port" at www.machsupport.com suggests they will not work.

phantomcow2 - A few months ago I purchased a ready made CNC system for my TAIG and had to return it because it would not work. I know now that it is because the designer left out a breakout board with level shifting.

[keebler303]

i would use an opto coupler with a 5v supply. The 3.5v would be enough to light the LED and then it would be boosted up to 5v on the output.

Matt

[CountZero]

STay clear of the usb-parallel adapters, they won't work at all for bitbanging. Only use is for connecting printers, at least they can help you to free up your real parallel port.

[pastera]

you can use a few 2n3904 transitors to boost the level, it won't be isolated but it's cheap and you can get the parts at Radio Shack.

A 4.7k base resistor and a 470-1k pull up resistor to 5 volts on the collector.
This would draw about 500uA from the port and deliver 2-5mA at TTL levels.

Aaron

[dgalaxy]

buy a candcnc breakout board and youll be in the goods

www.candcnc.com