LED support with Hagstrom KE72 (pics)

[Sasquatch!]

(Brought on by questions raised in this thread.

According to Hagstrom, this is the spot where they hook up:


Those solder points - from left to right - are:
GND - SCROLL - NUM - CAPS - (blank / not labeled) - 5V

Their reference card reads:

The KE72 also provides for signals for indication of the current state of the Caps Lock, Num Lock, and Scroll Lock LEDs.  These signals are TTL (5V logic) level, and can drive hi-efficiency LEDs through a series resistor.  Drivers may be needed to increase the drive current for LEDs or lights that require more than 1.5ma of current.  These outputs are active (LED on) when low.

I emailed Hagstrom asking if there should be some kind of connectors there. They replied:

The KE72 does not have a connector in that location. The reason is so that the end user can "customize" that location for their specific needs. That could mean the use of a connector (there are many different types and styles on the market), wiring directly to the unit, etc.
...
The connector pads are spaced at .100", which is a very standard spacing connector, available in one form or another from every connector manufacturer.  The type we use is the AMP MTA series connectors, available from digikey.com.  Your local Radio Shack would also have headers that could be soldered into that location as well.

The person I was corresponding with also told me that they offer a service where they will attach a connector if the unit is shipped to them.  I asked for details, and was told:

Just send it in to us, with a note stating that you would like a connector for the LED control, and be sure to include your return shipping address.  We would charge return shipping ($5.33), and $4.29 (includes parts) for attaching the board connector, mating connector, wires, and current limiting resistors for the LEDs.  We will even run unit though our KE72 tester to be sure it is in perfect working order.  We can ship the unit back within one day of receiving it here.

If you do send your unit in, please send an email notification as well so that we will know when to expect it.

So there ya have it.

[DZuroff]

You beat me to the punch on the post, Sasquatch, but I called Hagstrom today with the same question and received the exact same response and courteous service.  I think the $13.00 (approximate total for shipping both ways and parts) is well worth it to a person like me who has very little soldering skill!  

[MannyTC]

Dang, you guys got more info than I did and I talked to them a few times about it since last week. Never did they offer to add a connector. Weird.

Anyways, I shipped my KE72 for firmware upgrade to them on Tuesday and I just emailed them to see if they can add the connector before they ship it back to me.

Thanks for sharing the info

[Sasquatch!]

You beat me to the punch on the post, Sasquatch, but I called Hagstrom today with the same question and received the exact same response and courteous service.  I think the $13.00 (approximate total for shipping both ways and parts) is well worth it to a person like me who has very little soldering skill!  

You and me both, brother.  I probably could solder SOMETHING there, but it'd be ugly as hell.

Hey MannyTC, what's the firmware upgrade that you're getting for?

[RandyT]

....and can drive hi-efficiency LEDs through a series resistor.  Drivers may be needed to increase the drive current for LEDs or lights that require more than 1.5ma of current.  These outputs are active (LED on) when low.

I just want to give you guys a "heads up" on this.  1.5ma is virtually nothing when being considered for driving LEDs.

Fortunately, the write-up Kelsey so graciously provided for boosting the LEDs on the IPAC should also work for the KE72 as both are "active-low".  You might have to change the value of the resistors that sit between the output of the KE72 and the LED driver board though.

But if you are thinking that sending your KE72 back in for this connector will keep you from having to solder, I'm afraid that won't be the case in the end.  You'll still have more to do afterwards unfortunately.

Just trying to save someone some money in case they didn't quite understand the LED situation with this card.

RandyT

[Sasquatch!]

I just want to give you guys a "heads up" on this.  1.5ma is virtually nothing when being considered for driving LEDs.

Fortunately, the write-up Kelsey so graciously provided for boosting the LEDs on the IPAC should also work for the KE72 as both are "active-low".  You might have to change the value of the resistors that sit between the output of the KE72 and the LED driver board though.

But if you are thinking that sending your KE72 back in for this connector will keep you from having to solder, I'm afraid that won't be the case in the end.  You'll still have more to do afterwards unfortunately.

Just trying to save someone some money in case they didn't quite understand the LED situation with this card.

RandyT

Randy,

Thanks for the info.  I'm figuring on still using Oscar's writeup if I go with super-bright LEDs, since his scematic only used the IPAC for controlling (and not powering) the LEDs.

BTW, I know that the KE72 is 1.5ma...what's the IPAC?

My understanding (and please correct me if I'm wrong) is that I would be able to use the KE72 "as is" with standard LEDs (much like the IPAC), but I'd have to have a driver (like Oscar's plan" for super-bright LEDs.  Correct?

Thanks again.

[RandyT]

[quote author=Sasquatch! link=board=1;threadid=5322;start=0#35358
BTW, I know that the KE72 is 1.5ma...what's the IPAC?

My understanding (and please correct me if I'm wrong) is that I would be able to use the KE72 "as is" with standard LEDs (much like the IPAC), but I'd have to have a driver (like Oscar's plan" for super-bright LEDs.  Correct?

Thanks again.

I can't answer this with 100% accuracy but from what I know about the hardware driving the IPAC, I'm guessing it puts out at least 10ma, which is quite a bit more than what you are dealing with.

That's why you might have to use different resistors with Oscar's circuit.

If you want to use it "as-is" the LEDs you can use won't have a lot of output.  Also, if you try to overdrive it with brighter LEDs, you can damage the controller.


RandyT

[Sasquatch!]

I can't answer this with 100% accuracy, but from what I know about the hardware driving the IPAC, I'm guessing it puts out at least 10ma, which is quite a bit more than what you are dealing with.

That's why you might have to use different resistors with Oscar's circuit.

AHA!  You're online right now!  

But again, isn't Oscar's plan only using the IPAC (in my case, it would be the KE72) for the signaling, and not to power the LEDs?  So why would it matter?

[RandyT]

That's why you might have to use different resistors with Oscar's circuit.

But again, isn't Oscar's plan only using the IPAC (in my case, it would be the KE72) for the signaling, and not to power the LEDs?  So why would it matter?

The resistors limit the current going to the transistors.  If the resistance is too high for the weaker output, there might not be enough juice to turn on the transistor.

But then again, it might work fine  You'll have to experiment or do some research.

RandyT

[MannyTC]

Just got an email from Hagstrom and they added in my LED header and upgraded my firmware and shipped it back today. 1 Day turnaround!. Will let you all know how it works when I get it.

[Tiger-Heli]

I can't answer this with 100% accuracy but from what I know about the hardware driving the IPAC, I'm guessing it puts out at least 10ma, which is quite a bit more than what you are dealing with.

Seems like I read somewhere that I-PAC supports 20mA, I could be wrong also, though!

[RandyT]

Seems like I read somewhere that I-PAC supports 20mA, I could be wrong also, though!

Just looked up the specs on the microcontroller.

Maximum input Sink current is 16.5 mA tested @1 Volt.

RandyT

[Tiger-Heli]

Just looked up the specs on the microcontroller.

Maximum input Sink current is 16.5 mA tested @1 Volt.

RandyT

Maybe it was the MK40 that was 20mA!  (So many encoders, so little time!!!)

[Sasquatch!]

Just got my KE72 back from Hagstrom.  Here's what the plug looks like:


It came with a wiring harness that has 560 ohm 1/4 watt resistors built into the wiring:


I haven't tried it yet...I need to buy me some LEDs.  As a sidenote, my earlier posting that it put out 1.5ma of current was WRONG (even though that was a direct quote from Hagstrom, dammit).  The KE72 puts out 8.0 ma.  

[MannyTC]

Dang I thought I was going to get to post those pics first! I had sent my unit in 2 weeks ago for other work and the LED header. Looks real good. Can't wait to try mine out tomorrow when it comes.

[Sasquatch!]

Dang I thought I was going to get to post those pics first! I had sent my unit in 2 weeks ago for other work and the LED header. Looks real good. Can't wait to try mine out tomorrow when it comes.

I got the firmware on my upgraded too while it was in.  Unbeknowst to me, upgrading it erased the memory on it.  THANK GOD I still have the CFG file from two years ago.

[Carsten Carlos]

I can't answer this with 100% accuracy but from what I know about the hardware driving the IPAC, I'm guessing it puts out at least 10ma, which is quite a bit more than what you are dealing with.

That's why you might have to use different resistors with Oscar's circuit.

I designed this circuit/resistor for the I-PAC. You are right, for the KE72 you'll have to use a 3 KOhm-resistor instead of 1 kOhm.
I guess the transistor should work with this low current also, but can't test it out now to verify.

[Carsten Carlos]

You are right, for the KE72 you'll have to use a 3 KOhm-resistor instead of 1 kOhm.

Sorry, didn't read the correction with the 8mA.

Leave the circuit with 1KOhm, it will work. This way the current is 4.3 mA, no harm for your KE72.

[Sasquatch!]

Sorry, didn't read the correction with the 8mA.

Leave the circuit with 1KOhm, it will work. This way the current is 4.3 mA, no harm for your KE72.

Cool.  Thanks for the info, Carlos!