hello i want to express this thread further i want to know how can I connect the 3 pieces of lm3914 on to make a equalizer look LED sorry im Noob Thanks btw I dun speak english well a schematic diagram will do well so i can know how to connect it Thanks again

 

Can anyone help me with connecting multiple LM3914's together. I cant find documentation anywhere for using more than two, and I need 6 tied together (yep, 60 led's). I have breadboarded my 6 and it does work, but the resistor values for Rhi / REF OUT are driving me nuts.

From the data sheets, projects, etc, the values seem to increase (looks like double) as you increase chips, but the LED's brightness changes with each group of 10.

Is there a formula I can use to set these resistors so I can keep the LED current the same with each chip, or do I need to make 6 seperate external references for the chips .

It would also be nice to have an adjustment so I can vary the LED current of ALL 60 together (I need aprox between dim and 8mA as a full 10ma get the chip too warm for my liking)

Any help would be greatly appreciated

Datasheet

The currents in the Leds are set by the ref current on pin 7 set by R1, this current is 10 times the value , 7 to 13 mA in each led, (see page 9 datasheet)

to cascade them in series see page 18 datasheet, just make sure the first IC is the ref lo to ground and connect its ref hi to the next ref lo and so on , the last IC has the ref adjust set to the desired level from 1.2V to 12V.

 

Hello,

You just hyjacked an existing thread:
LM3914 HELP - Connecting multiple units

Now you have a thread of your own.

Bertus

 

thank you bros

 

Simply connecting multiple lm3914 together will only allow a voltage to be divided into 20, 30 or 40 segments instead of 10.

If you want a multi-band equalizer display, you will need a circuit that pulls out the relative power of different frequency bands in an audio signal.

You can use the following ship to separate the signal into seven frequency bands. There are some issues with this chip - only one output that must bu multiplexed back to your array of LM3914 chips.