LM3915 cascaded dot/bar mode switch

[humanNPC]

Does this work?

i added a resistor and a switch to the circuit of the datasheet... LM3915 (page 11, Pin9 internal circuit on page 9)

VCC 12V
V LED PWM 5V

while in dot mode
pin 9 is reverenced to LED9 minus 600mV and if below that threshold LED10 is switched off, this should work since the other reverence voltage is also in seris with a 20k resistor
Does LED10 really turn off if LED11 is on?

if switched to bar mode
with 12V on pin 9, LED11 should turn on fine if the threshold is reached but is it as bright as the other LEDs?
does the higher voltage of VCC interfere with the lower voltage driving the LED?


Sincerely

 

[alec_t]

Welcome to ETO.
According to the datasheet, pin 9 should connect directly to pin 3 (V+) for bar mode. Why does your switch connect it to 12V instead?

 

[humanNPC]

pin 3 & 9 will both be connected to the same 12V source, i think the reason why it says "directly" is that there is no problem with having a bigger voltage dropoff than 100mV