| The Craftmans Shop > New from Old |
| JCB 803 Saga |
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| AdeV:
IPA (not the beer) is Iso-Propyl Alcohol. Never heard it called Industrial Pure before - did you get the Chinese stuff? :lol: If you get bored of the linear bar graph, Sparkfun do some rather cool radial ones: https://www.sparkfun.com/products/11492 I bought a stack of LED products a while back, pretty sure I got some of the radial ones, you're welcome to one if you like. |
| awemawson:
... heat ... heat ... heat :bang: This module only consumes 2.2 watts at the worst case of 15v battery voltage (on charge) and all bars illuminated. Yet on my soak test the regulator was getting unacceptably hot (48 degrees C after a couple of hours) The dissipation is split about 50 / 50 between the regulator ( 15v -> 8v @ 150 mA = 1.05 Watts) and the LEDS & drive chip. I'm not too concerned about these as the dissipation is over a couple of square inches of board, but the regulator needs sorting. I'd tried using a largish area of the 0v copper pcb, and when that was insufficient bent up a small sheet copper fin that the bolt fixing the regulator retained. This improved things, but all the heat to the heat sink had to pass through the 3 mm bolt so not ideal. Not much point doing anything inside the case as the heat has to be got away. I hit on the idea of drilling a 10 mm hole in the pcb for the end of a cylindrical external copper heatsink to protrude into the case with the regulator directly bolted to it. I turned a 1" bar as per the picture below, tapped it's internal end M3, painted it matt black and super glued it to the rear of the main pcb. So at least now the regulator heat is exported fairly efficiently, and it's back on soak test to see the results You'd not think that a couple of watts would be so much trouble :bang: |
| DMIOM:
Andrew, If you want a cab heater, then ignore this ..... Otherwise, hot electronics => increased failure rates. It sounds like you're using a linear regulator, which is just chucking the power out as heat. I only uses linears on very small projects now; there are pin-compatible switching equivalents for most of the 78xx/79xx series regulators, and they can approach 90+% efficiency. If your board is now permanently populated with a linear regulator, I'd finding out what its minimum input voltage is and then running an upstream switching reg so that the linear reg does the least amount of work necessary. Dave |
| John Rudd:
Minimum delta-v for the 78 xxxx series is 2.0 volts..... There are drop in switchers on a pcb with a TO220 pin out....but expensive ( Ebay - typically £4 ish for a 7805 replacement) oops DMIOM already said.... Can't you reduce the led current a bit? |
| Pete W.:
--- Quote from: John Rudd on August 27, 2015, 10:31:14 AM ---SNIP Can't you reduce the led current a bit? --- End quote --- It's surprising how dim an LED can be out of doors when the sun is shining! Well, to be pedantic: the LED is just as bright but the high ambient sunlight causes the eyes to accommodate, so it LOOKS dimmer!!!! |
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