LED Lighting in Sequence Using Transistors

Add a simple digital counter chip and a 3:8 decoder chip. Drive the counter with a 555 timer IC. As the counter counts, the 3:8 decoder will give you 8 sequential signals that you can use to switch on each LED.

LM3914 - search for it. It is designed as a LED driver with a adjustable comparator.

Otherwise, you should share a resistor across the grounds of the LEDs to limit current. I am thinking you need to use voltage dividers (VDD>R>BASE>R>VSS) to accomplish what you are attempting.

yes indeed, the LM3914 !s designed to to exactly what you want !

I wish you lots of succes !

or try this one :

This one might be a possible sollutioin for you ...

Or if you need more than 8 LEDS : (You might want to to modify the input circuit, this one is designed for measuring temperatures ...)

As stated LM 3914 will do job- however many years ago I needed a simple LED voltage indicator for the charging system of my car- I used Zener diodes- I experimented till worked-the leds lit up in sequence- eg 9v6,11v,12v,13v,14v,15v. The leds all stayed on as v rose up & went off as v fell down in sequence- still have working in car- I used diff colours to represent low,normal, hi,over etc.

GA,

That is how I understood the OP wanted it done.

It looks as though I've missed out a stage in the calculation of the resistors.

In this spread sheet V is the voltage at the emitter of the first control NPN

The resistors are all in KΩ.

Vpot 1 (ie when V=1) is the voltage which would be present at the base of each driving NPN if the transistor was not there.

I've tried to keep the driving power (ie Rcomb) the same, and chosen E24 resistors to get the relevant voltage to 0.7V.

Of course you could do better if you used two resistors in each position or a series with a higher resolution. if you send me a private message with your EM address I will send you the spread sheet.

Use some comparator chips with each comparator set to a different voltage with voltage dividers as references. Apply your Vmin to Vmax to the top of all the dividers. Keep a constant Vcc to the chips and LEDs.