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Incognito LED - What kind?

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I don't remember if my Incognito came with any LEDs for the HDD activity indicator. If it did I lost them. Is there a specific kind I need to get? (besides the color of my choice :-)

 

Frank

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Well The Incognito board did not come with one.

 

Radio shack 276-022 or any LED , forward voltage, higher is dimmer and lower is brighter

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Hi, I just tried to replace the default LEDs of the 800 with new and brighter ones. I wanted to have a red one as the power-on light and a green one for the CF card activity, so that when busy, my newly made glass button on the Atari would give yellow when green and red are on. When the default LEDs were still in place the busy light on the left LED was going ok, but of course it was not very noticeable.

 

Well, I have only rudimentary electronic knowledge so I thought any LED would do...

 

After resoldering the red one on the right the result is great - really bright power-on light!

 

Now the problem - The green one (left) does not blink at all when the internal SMD LED on the incognito board is flashing. Polarity is correct and soldering is also ok. I tested it by applying voltage to the  led lines to the connector I made between the power board and the incognito.

It might be that the threshold voltage of the LED is too high and the voltage from the incognito is too low. However, it is very difficult to measure the voltage of the LED line with a multimeter when there are only short impulses.

I used two types of green LED. At first I tried a VF 3.0 - 3.2V one and then VF 1.8-2.0V after that. Both did not work in the left place on the board.

 

Does anybody know what is the voltage on the incognito busy line, so I can choose the right type of LED? Or is there something else I missed?

 

 

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7 hours ago, bugbiter said:

Now the problem - The green one (left) does not blink at all when the internal SMD LED on the incognito board is flashing. Polarity is correct and soldering is also ok. I tested it by applying voltage to the  led lines to the connector I made between the power board and the incognito.

It might be that the threshold voltage of the LED is too high and the voltage from the incognito is too low. However, it is very difficult to measure the voltage of the LED line with a multimeter when there are only short impulses.

I have exactly the same issue. I am 100% certain I installed things correctly but the HDD light I installed on my 800 doesn't flash even though the tiny SMD light on the Incognito itself does. I suspect Incognito can't produce enough current to flash a full-sized LED visibly, or at least, not the ones I had on hand when I did my installation.

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I found that the old red LEDs have a forward voltage of 1.6 volts - the new ones I got have more (1,8 or 3,0). Does the incognito really work with that low voltage?

 

Or is there a series resistor on the incognito board already that could be removed/bypassed?

 

It's a bit of a bummer really, that the only solution would be to use the low voltage LEDs, which are quite dark of course....

 

Flashjazzcat - where are you? Which LED did you use?

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5 minutes ago, bugbiter said:

Flashjazzcat - where are you? Which LED did you use?

Just any old 5mm LED randomly picked out of the parts bin, I'm afraid. It works fine.

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45 minutes ago, bugbiter said:

I found that the old red LEDs have a forward voltage of 1.6 volts - the new ones I got have more (1,8 or 3,0). Does the incognito really work with that low voltage?

 

Or is there a series resistor on the incognito board already that could be removed/bypassed?

As FJC pointed out, any LED you have will likely work just fine. In general LEDs are pretty forgiving for brightness vs. current limiting resistor in use. Over the years LED technology improved, thereby requiring less current to give a similar brightness. So if anything you'll have a brighter light source when putting a new LED in an older spec'ed application. However there is no fear of it burning out because of that (not the same as an incandescent light bulb in this regard).

 

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I wish it were like that - all the LEDs I have here are either so weak you barely see it flash (1,8 Vf) or they don't light up at all (3,0 Vf) with the incognito board

 

I guess I'll go looking specifically for LEDs with the lowest forward voltage I can find. (most likely red ones)

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21 minutes ago, bugbiter said:

... or they don't light up at all (3,0 Vf) with the incognito board. 

I think the green one I installed falls into that category. Forward voltage was about 2.7V and I get nothing on the HDD indicator at all. Alas. 

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At the moment I'm going for an orange one which seems to be the brightest one I got and is NOT red 🙂

 

I'll put in a higher resistor R201 (660 ohm instead 330) to dim down the now super bright red power led..

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Just a thought, I don't have one of these boards, but as it seems to be based on modern chips etc.

is it possible that the LED driver for HDD is 3.3V, that seems to be the current (joke!!) voltage.

 

If thats the case, then if the forward voltage is around 2.7V or more then the LED will hardly (if at all) light.

Edited by TGB1718
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7 hours ago, TGB1718 said:

Just a thought, I don't have one of these boards, but as it seems to be based on modern chips etc.

is it possible that the LED driver for HDD is 3.3V, that seems to be the current (joke!!) voltage.

 

If thats the case, then if the forward voltage is around 2.7V or more then the LED will hardly (if at all) light.

Yes that is an important point 👍 .

 

So I did some quick research and came up with what should be the perfect LED for this application.

 

4300H1LC.thumb.png.cd453dd783965ec1e8a41da219190d51.png

 

VF = 1.8V

IF = 2ma

Mouser Link

 

 

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I guess that's about the same as the ones that had been put on the power board 40 years ago 🙂

 

Anyway, I now have a blue (!) power- on light and a faint orange glow to it when the HDD is accessed. That's fine for me!

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Similar phenomen here... Bought two Incognito for an 800-U (UK) and an 800-P (GER). Any LED on the P6 header works with the 800-U, whereas any LED at the 800-P lits only once for a very short time at first access to SIO.

P6 gives me 4.6V at the 800-P. Exchanged the Incognito, but nothing changed. Very strange.

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Hey guys I know this is an old post but I just got around to installing my Incognito and ran into the same issue so I thought I'd share my experiences.

This is just cut and pasted from a post I made on Aussie Arcade.

 

After many months I finally got around to installing my Incognito but ran into a problem with the HDD led not lighting however I noticed there was a surface mounted one on the Incognito board blinking away.

After probing around a bit I found the led on Incognito (D1) was connected parallel to pins 1 and 2 of the P6 connector.

The problem is the on board smd led is drawing too much current for any external led to work properly. Short of finding a led that draws next to no current the only solution is to remove D1 from the Incognito board which I did and now my blue hdd not only works but is nice and bright. There really should have been a jumper on the Incognito board to disable the on board hdd led. The led's I used were common 5mm I had laying around from a breadboard kit, a red for power and blue for hdd both about 3-4 times brighter than the crappy red originals.

Another thing was I wanted to avoid cutting traces so my A800 could easily be reversed if the Incognito failed in the future. Basically all I did was follow the standard instructions however instead of cutting the trace I put some electrical tape under the led and bent the negative (cathode) leg out. This way all the wires are on top of the board without drilling any holes. I also opted to use a piece of styrofoam under the board to brace it.

Hope this helps somebody else in the future.

 

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