Posted Sat Sep 5, 2009, 1:03pm Subject: Adding LEDs to my Isomac - Electrical help?
I am getting ready to add the Ikea Dioder LEDs that Mark mentions in this coffeed post. The lights are powered by connections to a transformer, which is powered by a 2-conductor power cord with inline switch.
I want to mount the transformer into the machine housing, and feed it by tapping into the machine's AC input. I will dispense with the switch since the machine is on a timer, and the LEDs will just be on when the machine is powered.
The transformer is marked "Electronic Transformer for Low Voltage LED Lamps - INput 120V-60Hz 0.1A Output 12VDC 5W Max. CAUTION: Risk of electric shock. Dry location use only."
That last bit makes me hesitate (appropriately I think) about mounting in in the machine's enclosure. I am planning to mount it VERY high in the enclosure, at the front away from water tank, but it is possible that it might be splashed in very extreme circumstances (e.g. the heating circuit goes crazy and the pressure relief valve starts spraying water into the cabinet). I am not worried too much about damaging the transformer, but I am concerned about short-circuits, and my electrical knowledge is a bit limited in this regard.
My mediocre electrical knowledge and reasoning says: If the transformer gets wet, the risk of electrocution is from direct contact with water that makes a circuit from line-water-me-ground -- is that right? Assuming the machine's cabinet is grounded appropriately using the Earth lead from the AC power, then the risk of electrocution in this case goes to nil, since the circuit will be through the Earth ciircuit, right? Or is there a risk because the transformer is not fed by a 3-conductor wire with Earth grounding itself?
Any help/advice is certainly appreciated. :) I can of course always mount the transformer exterior to the enclosure and feed only the DC wires into the enclosure.
Dana Leighton - Espresso hack and CoffeeGeek moderator
if this is the product, I think you're probably pretty good to go as is, just mount the transformer high -
The picture is not great - but the transformer seems to be pretty well sealed. The disclaimer is pretty much standard from what I can tell.
Where and how you tie into the AC - and how you rout your lines, how you physically mount the transformer are what I see as you major areas of concern.
Note: I am not an electrical engineer, I have no electrical or electronic certifications - I do have a certain amount of experience with a soldering iron and custom audio equipment.
Posted Sat Sep 5, 2009, 8:34pm Subject: Re: Adding LEDs to my Isomac - Electrical help?
SwingT Said:
Found a link with on a page of one photo ... The picture is not great - but the transformer seems to be pretty well sealed. The disclaimer is pretty much standard from what I can tell.
Yes - it is pretty well sealed. A photo is attached. Clips and also screws hold the case together. The seal at the wire entry/exit is not as tight.
I am actually using the round LEDs because the Relax does not have enough room to mount the strips
Where and how you tie into the AC - and how you rout your lines, how you physically mount the transformer are what I see as you major areas of concern.
Yes. The AC lines can be routed from the power terminal strip, along the bottom and sides of the enclosure, secured by cable ties. I am ordering some fiberglass sheathing material to protect the insulation. The DC lines will run through an opening at the group head.
(Click for larger image)
Dana Leighton - Espresso hack and CoffeeGeek moderator
Posted Sat Sep 5, 2009, 8:48pm Subject: Re: Adding LEDs to my Isomac - Electrical help?
You are correct that with the case grounded you won't get shocked. Your plan sounds good and safe to me. Maybe you could post some picks when you get done, sounds cool.
Posted Sat Sep 5, 2009, 10:46pm Subject: Re: Adding LEDs to my Isomac - Electrical help?
Hi Dana,
I can give you a circuit to drive the LEDs from the AC supply with no transformer. It is simple and efficient and if you don't need line isolation it works fine. Let me know the specs of the LEDs and I'll calculate the values, draw the schematic, and scan it. I'm still not much good at CAD.
I am out of town now but after the weekend I should have access to a scanner.
Basically the circuit is a bridge rectifier and a film capacitor to set the current.
Phil
dana_leighton Said:
I am getting ready to add the Ikea Dioder LEDs that Mark mentions in this coffeed post. The lights are powered by connections to a transformer, which is powered by a 2-conductor power cord with inline switch.
I want to mount the transformer into the machine housing, and feed it by tapping into the machine's AC input. I will dispense with the switch since the machine is on a timer, and the LEDs will just be on when the machine is powered.
The transformer is marked "Electronic Transformer for Low Voltage LED Lamps - INput 120V-60Hz 0.1A Output 12VDC 5W Max. CAUTION: Risk of electric shock. Dry location use only."
That last bit makes me hesitate (appropriately I think) about mounting in in the machine's enclosure. I am planning to mount it VERY high in the enclosure, at the front away from water tank, but it is possible that it might be splashed in very extreme circumstances (e.g. the heating circuit goes crazy and the pressure relief valve starts spraying water into the cabinet). I am not worried too much about damaging the transformer, but I am concerned about short-circuits, and my electrical knowledge is a bit limited in this regard.
My mediocre electrical knowledge and reasoning says: If the transformer gets wet, the risk of electrocution is from direct contact with water that makes a circuit from line-water-me-ground -- is that right? Assuming the machine's cabinet is grounded appropriately using the Earth lead from the AC power, then the risk of electrocution in this case goes to nil, since the circuit will be through the Earth ciircuit, right? Or is there a risk because the transformer is not fed by a 3-conductor wire with Earth grounding itself?
Any help/advice is certainly appreciated. :) I can of course always mount the transformer exterior to the enclosure and feed only the DC wires into the enclosure.
Posted Sat Sep 5, 2009, 10:47pm Subject: Re: Adding LEDs to my Isomac - Electrical help?
It took only about an hour to finish the installation. I skipped the fiberglass insulation because I could keep the wires away from hot water lines using cable ties and mounting bases. Here's a picture of the installation on the inside of the machine. A full gallery of pictures is at this link
I cut the plug and switch off the AC line, and crimped quick connect and terminal blade to the wire, and connected to the AC barrier block. The AC line runs up the side of the case to the transformer, then the DC line exits to where the machine's controls are.
(Click for larger image)
Dana Leighton - Espresso hack and CoffeeGeek moderator
Posted Sat Sep 5, 2009, 10:51pm Subject: Re: Adding LEDs to my Isomac - Electrical help?
This view is from the machine's right side. When the DC line enters the area where the controls are, it terminates in a 4-terminal block that the LED's DC lines plug into. This rests on top of the switches away from the hot water lines. Similarly, the LED's wires are bundled up and rest on wires away from the hot lines. The LED wires feed through the opening where the group head is and are secured by cable ties and mounting bases so they stay away from the heat.
(Click for larger image)
Dana Leighton - Espresso hack and CoffeeGeek moderator
Posted Sat Sep 5, 2009, 10:56pm Subject: Re: Adding LEDs to my Isomac - Electrical help?
And the final mounting of the LEDs. There are 2 more in the package, and if these go not give enough light, then I may mount the other 2 on the side of the case, although that will make case removal a bit more complicated.
(Click for larger image)
Dana Leighton - Espresso hack and CoffeeGeek moderator
Oh wow -- Thanks so much for the offer Phil. I've got the transformer mounted fine now, and there's plenty of room in the case. If it burns up I'll let you know.
Cheers, Dana.
Dana Leighton - Espresso hack and CoffeeGeek moderator
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