Can I run the express without the heatsink?

[sittinguphigh]

Can I run the express without the heatsink? And if so, what is the amps per channel I can run?
I'm not going to run more then one set on LED string light per channel. Maybe 70 bulbs per string at the most. Trying to put everything in one box. Small as possiable.

[Greg]

I seem to recall RJ saying that you could but not to pull more than 1 amp per channel, but I could be wrong on that.  Running a string or two of LEDs per channel shouldn't be an issue at all.

Greg

[rm357]

Sure you can, you are just limited on the power. As the triac works, it generates some heat. Too much heat = meltdown, fire hazard, dispersal of magic smoke, etc....

No heatsink - better stay below 1 amp/channel for safety reasons

The LYNX heatsink gets you to about 4 amps/channel, but at that level you will run into limits on your source outlet pretty quick. With the two power cord configuration, you can have up to 20 amps on the first 8 channels and 20 amps on the last 8 (assuming you have two 20 amp outlets on independent circuits). With the one power cord configuration, 20 amps across 16 channels is only a little more than 1 amp per channel anyway unless you never turn them all on at the same time....

RM

[sittinguphigh]

So if I'm correct I could run 110 watts per channel.  The most I run on any on of my strings in 5 watts. I shouldn't even come close to over heating the PCB.

[Kwajtony]

This was talked about Here

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I do not use a heat sink on me LE's that drive leds.

[sittinguphigh]

Ok. If I get this right. With out the heat sink. You will get 2 amps or (220 watts) per channel.  But you only hook up one power lead. But you have to use the jump point? I don't understand this. Would you explain this?

Thanks

[jekalaka]

On reply #19 on the 'power cords' thread RJ says:

'1 Amp a channel is fine with no heatsink ...(cut)....  If you want more than 1 amp on a TO220 case since it can only dissipate so much heat in the area avaliable you need to attach it to something with a good path for the heat to move fast into it. A heatsink with a little heat compound is ideal.

No it will not self destruct at 2 amps as a few will jump in hear to say but it is a good idea to keep them cool.'

It doesn't sound like you are going to come close to even 1 amp a channel though  .

The single power lead hookup is explained in the express manual on the wiki please see:

Appendix A single power input mod

It isn't mandatory to do it this way, but it will save you one less dang cord to have to fight with while setting everything up.

I hooked up everything on my expresses with 6 foot cords, what a mess every time I go to use it I spend forever untangling cords. My next ones will get 3 footers.
(of course, if I wasn't too lazy to wrap and bundle the cords I wouldn't have to fight them every time either  )

Jon Wimmer
Ekalaka MT

[Kwajtony]

Ok. If I get this right. With out the heat sink. You will get 2 amps or (220 watts) per channel.  But you only hook up one power lead. But you have to use the jump point? I don't understand this. Would you explain this?

Thanks

I'm going to make a ..... of myself, but I assume you are asking about the tie between the two halfs of the LE for power Input/Output -- in the middle of the LE on the between  channels 8 and 9 the AC sources are split so the unit can be powered by two seperate plugs.  There is a provision to "Jumper"  the two halfs together so it will provide AC  on 16 Channels from one source.  If you look at the assembly instructions I'm sure you will find where it says to install the jumper if desired.

[tbone321]

Ok. If I get this right. With out the heat sink. You will get 2 amps or (220 watts) per channel.  But you only hook up one power lead. But you have to use the jump point? I don't understand this. Would you explain this?

Thanks

That's not really what was said.  What was said is that the Triacs are good for 1 amp without a heat sink and someone else said that they could probably handle 2A without blowing up instantly but I think that 2A would get them very hot.  To increase power delivering capability RJ split the power input into two banks with each bank powering 8 channels.  Since each bank could be hooked up to a 20 A source, it gives the express a possible max of 40A or around 2A per channel if all of the channels are on at the same time.  If you don't need that much power you can connect both side to the same source and RJ has provided jumper points to connect the two banks together.  With these jumper points connected you only use 1 input power cord but you are limited to 20A total power which means if all channels are on you are limited to about 1 amp per channel.

[sittinguphigh]

Ok. I don't need more then 1 AMP per channel in the LE. So do I have to change some thing in the regular LE assembly?

[tbone321]

You don't have to change anything.  Since your power requirements are low you can connect the jumpers on the lower portion of the board near the triacs and run it on one input power cord if you wish.