New Front Panel parts - 7-segment LEDs getting scarce!

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Terry Smedley

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Jun 24, 2021, 5:54:58 PM6/24/21
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This is just a heads up in case you're thinking of building the new front panel.  The LEDS specified for that board (Liteon LTS-6980HR) are getting hard to find.  Futurelec, Mouser, and Digikey all show out-of-stock with extended restock times.  Quest does have a few available, and Norberto found a link at pcbelectronics which claims to have an almost unbelievable number in stock.  You might consider grabbing stock from Quest (or anywhere else you can find these) while they still have some.  

There are some alternatives (see the Amazon link), but these have not (yet) been tested in the new front panel board.  But the Amazon LEDs have worked OK in the Heath front panel. To stay within datasheet current maximums a resistor change is required, but they have been used successfully with no resistor change by at least one member.

Everything else on the front panel BOM was readily available through one or more of the usual sources as of yesterday.

Links:




Norberto's web page for front panel, including BOM: : http://koyado.com/heathkit/New-H8-Website/h8-front-panel.html

I believe the only thing missing from the BOM is the 1/8" flat bar from Home Depot.  Norberto will be posting information soon on the beautiful custom keycaps he obtained. 

Terry







norberto.collado koyado.com

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Jun 24, 2021, 9:07:04 PM6/24/21
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Great work Terry!

On the Custom keycaps, I will be posting tonight the Backlight keycaps ordering instructions; the ones that needs a bright 3mm white LED.  

Let me know if interested on the regular H8 custom keys (not backlighted). Even if you install the bright 3mm white LED, there are two jumpers on the H8 FP to turn off such LED's. All backlight LEDs should be installed. I tested with the ohmmeter every MX switch and every LED to avoid de-soldering if part fails to work. 

I'm still working on the assembly guide and hope to have a draft by weekend or early next week. Will do another pass on the BOM tonight as well.

Thanks,
Norberto

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Terry Smedley

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Jun 25, 2021, 12:06:02 AM6/25/21
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Norberto:

Count me as one who is most interested in the non-backlighted keycaps.  From the photos you posted, I thought the opaque keycaps were very nice.  I'm also thinking of using a similar approach to replace the very (electrically) noisy keypad on the HERO-I robot with the opaque keycaps (and MX switches of course).

Thanks!

Terry

Norberto Collado

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Jun 25, 2021, 1:24:29 AM6/25/21
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FP BOM updated. The website with the Custom Key caps deleted the link to order more keycaps. I just send an email to put it back and to send me the new links. As it has been a while, perhaps they deleted as no orders has been placed since them.

 

Thanks,

Norberto

dwight

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Jun 25, 2021, 5:40:59 PM6/25/21
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I don't think they have the exact 7 seg LED but Anchor Electronics has several types of these. It is worth looking at if you are having problems finding them.
The DIP pinouts are relatively standard. You just have to match DP and common Anode/Cathode.
Dwight


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Subject: [sebhc] New Front Panel parts - 7-segment LEDs getting scarce!
 

Glenn Roberts

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Jun 25, 2021, 9:07:35 PM6/25/21
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I’ve had good luck just ordering off eBay. As long as it’s .56” common cathode.  Looks like it’s been a while since I bought any of these but last I did I think I paid $8.50 for 10 units.  I must admit I’ve never checked the power specs, but then again have never had any problems…. Perhaps something like this?:

 

https://www.ebay.com/itm/224320030789

Thomas Riesen

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Jun 26, 2021, 8:12:42 AM6/26/21
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This new LED displays work well, bought recently also this:  www.ebay.com/itm/121363629852?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

But they are very bright, so, you have to replace all eight digits and/or to change the resistor value ... the red matchs not the old style type color ... 

Thomas

Glenn Roberts

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Jun 29, 2021, 9:58:04 PM6/29/21
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Pretty sure these “Ele-parts” ones are what I bought some time ago.  FYI I did not change any of the resistor values and haven’t had any issues…  so I’ve had good luck.

norberto...@koyado.com

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Jun 30, 2021, 4:22:29 AM6/30/21
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Each digit on each .56” common cathode is only “on” for about 1.5ms, so there is no need to change any resistor value. If the circuit that controls the 1.5ms pulse fails, the LED display will be very bright and it might damaged the LED display “only” when booting HDOS or CP/M as they do not clear the FP display because  they rely on the 1.5ms circuit to do its job.

 

If you want to control the LED brightness, then you will need to change the 1.5ms pulse to 0.9ms or something similar.

.

Norberto

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