Topic: USB / TTL circuit info

[Lazerjock]

Wow! Gary you are fast.
Here is the link to the USB to TTL converter. I don't know why but you have to scroll to the bottom of the page to see the product after the page loads. At least on my computer.


http://www.circuitgizmos.com/products/cgu401/cgu401.shtml

Lazerjock

[Fanny Pack]

Thanks for the link.  This is going to be fun. 

[Lazerjock]

Here is another link to the Online Developer Notebook for the USB to TTL board. It isn't real obvious how to get there from the original link I sent.

http://www.usbmicro.com/odn/index.html

Tonight I will try to post the FET I used and a simple wiring diag. showing how to connect it to the USB board.
It is very simple.

Lazerjock

[Fanny Pack]

Thanks, and no rush.  It will be awhile before I am ready to actually start communicating with a device.  First I have to add support for TTL/DMX layers, multiple devices, multiple scanners, etc.  I don't really have to do all that to add TTL support but since I will be working in all the same code it makes sense to do that.  Once I get done with all of that Spaghetti will be mostly complete.  I may add some new effects or tweak here and there but other than that all of the functionality will be there that I ever planned.  I do plan on adding a frame editor similar to LaserBoy at some point but I may hold off on that and do some work on Wet Noodles.  So much to do.

[Lazerjock]

For anyone interested.
Here is the schematic to connect the USB to TTL board to an external device such as a GM-20 actuator. I use it in my projector to steer the main beam into my Lumia wheel as well as the Machita diffraction gratting. This could be used to control almost anything (Strobes, Smoke Machines, Stage lights) with an added relay to switch 110 VAC.

The FET I'm using IRFU120N can handle (according to the data sheet) 9.4 Amps cuntinuous @ 10 Volts DC max .

I'm using 12 Volts DC which gives me 7.8 Amps to work with. I am not drawing anywhere near 7.8 Amps. I may be drawing 1 Amp. So these FET's have pleanty of head room and they're small too. I would recommend a heat sink if you plan to draw more than 1 Amp.

The FET's are available from Digi-Key for .62 each with no minimum required. The Digikey part #  IRFU120NPBF-ND

Feel free to contact me with questions.

Lazerjock

[James]

That's AWESOME!

It's so simple!

Will it switch +5VDC?

I've been wanting something like this for years!

(Shows you how lazy I am!) 

I wanted to use it on the output of a parallel port to switch LEDs.

I was thinking about doing PWM for dimming and mixing RGB.

James. 

[drlava]

You might want to put a reverse biased diode parallel with the load to shunt its back emf at turn-off to protect the FET.  Some loads are inductive, like shutters.

[Fanny Pack]

  You need to come up with a DrLava TTL driver/protection board.

[Lazerjock]

You might want to put a reverse biased diode parallel with the load to shunt its back emf at turn-off to protect the FET.  Some loads are inductive, like shutters.

Yea the original design had a reversed bias diode, but I didn't have them at the house. With SELEM looming I went without it and it seemed fine. When I drew the schematic I ment to add it and forgot.
Sorry.

I updated the schematic.

Lazerjock

[Lazerjock]

That's AWESOME!

It's so simple!

Will it switch +5VDC?

I've been wanting something like this for years!

(Shows you how lazy I am!) 

I wanted to use it on the output of a parallel port to switch LEDs.

I was thinking about doing PWM for dimming and mixing RGB.

James. 

James,
This FET is capable of switching 100 volts max. I can't see a minimum drain voltage anywhere on the data sheet. My guess is it will have no problem with 5 volts.

Lazerjock

[Fanny Pack]

LazerJock: I should have something for you to play with soon.  Not a finished product but you will be able to see if things work.  But, are you still around?  Haven't heard anything from you lately.

[cfavreau]

I would suggest finding a FET with built in back EMF diodes.  There are plenty of them out there that can handle quite a bit of voltage and current... and they are cheaper than Bipolar transistors...

[cfavreau]

FQP30N06L-ND

http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=fqp30n06l&x=0&y=0

N-Channel Logic Level
60V @ 32A
TO-220 Case

$0.83 in single quantity.

[James]

I'm so glad to see people openly discussing electronics!

I love to see sharing for the advancement of technology in general.

More, more, more!!! 

James. 

[Lazerjock]

I'm still here.
We (the wife and I) are dealing with some family problems.
Her sister has breast cancer and is having a double mastectamy today, and my aunt just had brain surgery to remove a tumor last Monday.
My wife's position at work was eliminated due to cut backs. She still has a job, just back in the lower position she started at.

It's been a little rough the last few weeks. I did throw a big birthday party for the wife last weekend to try to bring us out of this funk. I broke out the laser projector after dark. Most of the guests never saw anything like it before.

Lazerjock
Chris