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  • 9 months later...
On 5/22/2019 at 8:00 AM, BeeryMiller said:

Someone has created a 5.25" bracket for mounting a DREM. The link to the 3D file is at:

 

https://www.thingiverse.com/thing:3555045

 

Is it possible for someone to print a couple up for me? Cost?

 

Thanks.

Beery

 

Just a FYI for those needing the DREM bracket or any other 3D object printed.  I saw a post someplace Greg had referenced some time ago that one could submit your STL files to MakeXYZ.com .  I submitted the set of STL files for the DREM and had two faceplates made with shipping for under $20.  I could have also had the body to support the DREM 3D printed as well, however, I found it looked almost identical to the black plastic bodies for holding 3.5" drives.  So I did not print the drive body, just turned it 180 degrees and used the other end.  I had to trim the corners to square things up, but I was able to superglue the faceplate to the body (Note:  One had to do that with the original design as well).

 

I also did not have the buttons printed either.  It was a very good print job.

 

The original designer of the bracket did not place a hole for the mini-USB port as I guess he never imagined the firmware needing to be updated, however the designer of the DREM hardware has updated the firmware at least twice.  So, I took a drill and made a couple of holes, and then trimmed things out so I could reprogram the DREM should the need ever arise again.

 

I'm pleased.


Beery

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One thing that I always thought would be cool since 3D printers became available is a modified key strip holder.  I would be "a little taller", but with LED's in the body.  One could drill a small hole into the TI, under where the strip would attach to run the wires to power.  When the TI is turned on, the LED's would also come on.  I figured it might be nice for those "late night sessions".

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58 minutes ago, --- Ω --- said:

One thing that I always thought would be cool since 3D printers became available is a modified key strip holder.  I would be "a little taller", but with LED's in the body.  One could drill a small hole into the TI, under where the strip would attach to run the wires to power.  When the TI is turned on, the LED's would also come on.  I figured it might be nice for those "late night sessions".

you should design one in tinkercad.com  it's stupid easy to use even someone with no experience could design something. I used it to design my cart holder 

 

Greg

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16 hours ago, --- Ω --- said:

BTW - If you were to connect 5 LED's to the TI for keyboard lighting, where would be the best place (in your opinion) to tap the power.  I'm also assuming a resistor would be part of the equation.

 

To get the resistor value, test them out with an external power source starting with 330 ohms.

 

      SW1
+5V -o_|_o----+------------------------
              |              |
              R1             R2
              |              | 
             ---            ---
             \ /  LED1      \ /  LED2
             ---            ---
              |              |
GND ----------+--------------+-------

 

1. See this easy guide: https://learn.sparkfun.com/tutorials/light-emitting-diodes-leds/all

 

To avoid any math, that guide says "start with 330 ohms resistor, then adjust."
 
There is a voltage drop across the LED.  It depends on the color. In my experience, red is the least, blue or violet is the highest (I don't remember white) sometimes too much for a coin cell battery to provide.

 

With math,

 

Light up the LED using that 330 ohms, get out a voltmeter and measure the drop across the LED leads. Call this V_led. 

 

If you like this brightness, compute the current I_led: Assuming VCC is your test power voltage, then

 

I_led = (VCC - V_led) / R.

 

If you tested with one VCC, like 3V or whatever, and the console will provide 5 or 12V, you need to recalculate a different resistor to keep this brightness the same.

 

2. Doing it another way, work backwards from that current, OR the current listed on the package (that assumes you got a package, not just piles of random LEDs from China.) Your LED might need around 20 mA. Solving for R, assuming VCC=5 and V_led = 1.5, then

 

R = (VCC - V_led) / I_led = 3.5 / 0.020 = 175 ohms. 

You would grab a 150 or 180 from your assortment of resistors. 

 

To understand where those standard ohm values come from:  http://www.resistorguide.com/resistor-values/


3. In the 4A, I dunno where to best hook them up, but any VCC pin will do, preferably close to where the  power connector hooks up. One thing though: connect each LED with its own resistor. Each LED+Resistor goes in parallel, like the schematic above. If you put them in series, the sum of voltage drops will be too much. If you put all the LEDs in parallel after just one resistor, some won't turn on.


              
4. Much bigger project: TI makes a great LED driver chip, the TLC5940, which even lets you calibrate each LED's brightness and save it in EEPROM.  I use these to drive an array of tiny laser pointer red LED lasers - which all have different V_led (and worse, they die easily if they get too much current.)


At run-time you can set value for each brightness.

 

The TLC5940 doesn't care how slow your input is, so it could be interfaced using 3 of the 9901 pins (the essential signals are XLAT, GSCLK, and SIN.) GSCLK can be connected to the 4A's PHI3 clock, or the 3.5 MHz clk out of the 9918A.

 

One TLC5940 drives 16 LEDs, so you could have a bank of LEDs on the function strip. Software could turn the on individually or blink them. 

 

http://www.ti.com/lit/ds/symlink/tlc5940.pdf

 

Search eBay for TLC5940 DIP because apparently the DIP is no longer offered.
 

 

 

Edited by FarmerPotato
clarified
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1 minute ago, arcadeshopper said:

you won't like it, but the best place to get power is an external brick the TI supply isn't designed to run anything but the TI.

 

"Best", possibly.  However the TI was designed to power some parasitic devices in the past like the RF modulator and the speech synthesizer.  Now days most of us have long ago disposed of the RF modulator, leaving some electrical "overhead".  Small LED's require very little, so I did not think it would even be much of a factor.

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"Best", possibly.  However the TI was designed to power some parasitic devices in the past like the RF modulator and the speech synthesizer.  Now days most of us have long ago disposed of the RF modulator, leaving some electrical "overhead".  Small LED's require very little, so I did not think it would even be much of a factor.
What voltage

Sent from my LM-G820 using Tapatalk

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55 minutes ago, --- Ω --- said:

 

Well, having left the arrogance of youth behind and knowing there are smarter people here than I who know the TI better, it never hurts to ask. ?

 

You could do it with a battery. A coin cell will run an LED for about a day. (no resistor needed to limit current). Two AAs will also do it.

 

 

 

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Take a slip on strip as your first guide to slip into the TI case,top.

Build your led array on something a little narrowed than that first strip.

Enclose it with a bottom and power it from a side wire to external power.

Glue the bottom to the strip so you can pull it out whenever you want and slip it back in when needed.

 

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