oldtuckunder Posted January 24, 2018 Author Report Share Posted January 24, 2018 Alan - please note that I have found some data on the heat sinks of a similar-sized unit which states that additional heat sinking or fan cooling will be required if the modules are run at max output. I noticed on the board that there are two connection points marked +/- with the legend "fan" etched on the board. I have a cupboard full of little PC cooling fans so may see about incorporating one. Of course I do have a nice freon filled heat sink, but hopefully that would be overkill Alan Quote Link to post Share on other sites
RobH Posted January 24, 2018 Report Share Posted January 24, 2018 Cool ! Quote Link to post Share on other sites
rogerguzzi Posted January 24, 2018 Report Share Posted January 24, 2018 Yes there are different types - this one is a buck converter but they quote input 4- 30v and output 1-30v so it should work if the spec is to be believed. As Alan is intending to use 12v (plus a bit ) in and 12v out that should be Ok . Hello Rob Electronics is not my field but I thought there is a voltage drop caused by the diodes of 0.5 to 1 volt? Which would be ok while engine is running at speed (14+ volts) but at tick over 12.5 volts would give less than the 12 volts But will probably not matter as the 12volt is going to be dropped in the Megajolt unit anyway! Roger ps unless they have invented 100% efficiency! Quote Link to post Share on other sites
RobH Posted January 24, 2018 Report Share Posted January 24, 2018 Yes what you say is true Roger but these things are not linear regulators as you are perhaps thinking - it is not a case of having a component in series with the feed which will inherently reduce the voltage at the output. In a switching regulator the input voltage can be anywhere in a wide range and is used to drive an oscillator which, via a transformer or choke, produces a voltage which when rectified gives the desired output. The output voltage is set by the feedback circuit which controls the oscillator and depending on the type of converter the output can be higher, lower or the same as the input. You are right in that the 'margin' which we were discussing is indeed the extra voltage that a 'buck' converter needs over the output in order to work and it may well be that 12v is not attainable at tickover. Equally if you used a boost converter you might not be able to reduce the voltage as low as 12v, because the margin runs the other way. That is why a buck-boost converter would be the preferred type as that would not have any margin at that point of its range but unfortunately there don't seem to be any readily available with sufficient current capability. I am not sure what units Alan is going to power from this but they probably are not so critical on input voltage that if the unit will only go to (say) 11v instead of 12v it would be a problem (fingers crossed). Quote Link to post Share on other sites
oldtuckunder Posted January 24, 2018 Author Report Share Posted January 24, 2018 I guess the easy way to find out is when I hook it up to a charged car battery and bung a meter on the output and measure it. Guess when engine is back running I can do the same with engine at tickover (not that my tickover is ever less than around 950/1k) I assume best way to measure would be with a small load like a light bulb running off the output rather than unloaded or doesn't it matter? Quote Link to post Share on other sites
RobH Posted January 24, 2018 Report Share Posted January 24, 2018 Yes some sort of load is a good idea for that test rather than open-circuit. Quote Link to post Share on other sites
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