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I found this schematic of 10 Led car voltmeter with adjustable lower and top voltage limits. **broken link removed**
I tried to make 20 led version, but I have a problem led 10 stays always on if voltage is above it's limit. In bar mode you can't notice it but it's clear in dot mode.
I tried to find the error to no avail. Please see attachment.
I tried to make 20 led version, but I have a problem led 10 stays always on if voltage is above it's limit. In bar mode you can't notice it but it's clear in dot mode.
I tried to find the error to no avail. Please see attachment.
I have added pin numbers by hand and update the above schematic.
Thanks, but it is still a negative pic. It should have dark lines on a white background.
Do you mean the connections are not required between IC2 pins 9 and 11; IC2 pin 1 IC1 pin 9 ?
The datasheet shows how to do it. In the BAR mode, you are shorting pin11 to the positive supply so its LED will never light.
The second LM3914 has its pin9 connected to its pin11 (but not to the positive supply) only in the DOT mode. Then pin11 has a 20k resistor to the positive supply so that pin9 is high when the LED is turned off.
Well I'm trying to make not bar but dot mode here. How can I short second LM3914 pin9 to pin 11 not to positive supply if leds are on a positive supply side? You can see that because wires are colored red?
The 20k resistor is connected as data sheet shows, or did I miss something and connected it wrong?
Can you draw wires on my schematic to make it clear?
I have made another schematic more easy to read, but still same problem with led10.
20k resistor is connected to 1st LM3914 as shown in datasheet diagram.
LM3914 IC1 mode pin 9 connected to LM3914 IC2 pin1 as shown in datasheet diagram, then a wire goes to led 11.
The led 10 is extinguished as data sheet said, but now how to turn it back on?
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