If you look at the circuit, all the leds have their anodes connected to +12v, room on row 10 where I've just shown a single +12 connector, plus you could link to the spare row 11 below. For the caps I was thinking of tantalum electrolytics, Maplin have both sizes, but they have those sizes in the cheaper aluminium as well. Ta bead = WW58N (39p) Al radial = KQ61R (17p), VH02C (14p) ps - You can trim quotes you know, my scroll finger hurts
Am I right in thinking the PONR circuit (and mm's potted variation)will have at least half the bargraph always lit when fans are operated in the 6-12v range? What changes are needed for a 5-12V range covering leds 1-10?
Yes you are correct. A variable resistor between pin 4 and GND is needed to set a zero offset. Check out the data sheet.
Thanks for confirmation, the Expanded Scale example (p9) threw me with the seperate LED psu, but I'm assuming that's not compulsory Looks like NS prefer to make the meter fit the signal level, rather than (like PONR) attenuate the signal to the 1.2v range of the raw chip. Back to the drawing board...
Sorry about that Point was, the circuit shown will read 0-12V over the 10 leds, so the column of lights will grow 1 light for every 1.2v increase, and with fan control the bottom 5 lights (up to a 6v level) will generally always be on. Bit of a waste of the ic's capabilities IMO. I was fancying a display with just 1 light on at 7v and all 10 on at 12v, so it would show fan voltage to 0.5v sensitivity. There are some examples of how to do this on the datasheet, but not entirely applicable, as you also need to reduce the fan signal level - the 3914 can only measure voltages up to about 2v less than the supply volts (ie up to 10v), so you first need to reduce the signal with a pot divider as macroman shows. The stripboard layout will work ok, but only like the PONR system.
Ah thanks for the simplton version for me I should have the circuit done over the weekend just waiting for some parts
Well I've finally finished the first part of the rheobus circuit And its working fine , one of the heatsinks got waaay to hot for my liking in testing so I am gonna add one of the thermaltake ones for extra cooling. Thanks to cpemma for the guide as a simplton such as myself could use it so it must be good Now for work on the led array part
You can boil water on a 317 heatsink without any damage :dude: I tested a car stereo with one, now that gets them warm.
I'm gonna be running them at around 5v all the time so as much heatsinking as possible is the order of the day I could cook a very small egg very quickly on these
Just one more quick question do I need resistors between the leds and the 12v line I would imagine I do ? Cheers Gordy
Ok I'm guessing the capacitor exploding and bursting into flames is not a good sign Any idea's wot I did wrong ?
I'm currently working on incorporating the same two circuits that gordy_hand showed. I have already assembled the whole circuit but I haven't tested it yet since I'm still waiting for my new PSU to come by mail and have my old PSU as a mod power supply. I maybe trying that 10k preset replacement also. Question on the 10k rheo to be used (i'm not that really familiar with trimmers/pots that much), I'm guessing the middle pin is the wiper, so which outer pin goes to the fan and which goes to the other? Let's base this on looking at the rheo with the knob pointing towards you. Code: wiper | 1 2 3 | | ? ?
It was capacitor c2 on the voltage monitor ciruit I would love to know wot did it before testing the other one for the other fan channel it scare the bejesus outta me and nearly set fire to my chair
Thats the thing I thought I had ? I had run the circuit a couple of times b4 with no probs , I couldnt get the led's to work tho
