There are 7-Segment Voltmeter kits with 3-Digits at aliexpress.The cost is lower than what you do by yourself
I notice some kind of adjustment on the back, I think its for resolution? using at lower voltage?...
Your k7tty.com link appears suitable to provide expanded scale. I built similar voltmeters. It has instant response to voltage. I can see where it drops to in the first 1/10 of a second when cranking the engine. Thus it tells me something about battery health.
I adjusted mine to yield a range of 7 to 16V in steps of 1V. (Two or more 3914 IC's can be cascaded for closer resolution.)
I know of no other type of meters that gives such instant response, neither my old-fashioned D'Arsonval needle type nor digital type.
No, it won't work; because the driver for the display takes the power from the same battery and the ground is common.
You need to have an offset (say 10V) and then apply the voltage to the input. The ground is common...
Let us say you put a 10V zener and a 10K resistor to the battery; The voltage across the resistor will now be reduced by 10V.
Its a long time since I used an LM3914 but I think it's possible to lift the bottom of the divider chain above ground to set the minimum reading.
R7 is already marked "2W". You must not ignore this information.1. The 83Ohm resistor seems to get warm. Very warm.
Hi,
C7 is already marked "2W". You must not ignore this information.
Did you install a suitable resistor?
Klaus
Is there any easier way than just using a blank board and trying to forcefully solder everything and... um... I've never done that before
Thanks.I think you meant R7.
And this I think exactly is the point "why".I'm not sure why that is necessary as the LM3914 already contains current regulated outputs.
Agreed Klaus, but using the diodes as a shunt voltage regulator like that means they have to pass more than the combined current of all the LEDs in 'on' state to ensure the voltage stays steady, that is very inefficient. I suppose it really depends on how much current the LM3914 is programmed to pass through the LEDs but a smaller resistor in series with each LED would certainly avoid the single hot component and only illuminated LEDs would create any heat at all.
Brian.
This makes some sense to me. I think I want to try what you are saying, remove the big fat resistor and use smaller individual resistors for each LED.they have to pass more than the combined current of all the LEDs in 'on' state to ensure the voltage stays steady, that is very inefficient.
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