inverting and amplifying LM3915 VU-meter-IC

Miscellaneous
1

hi folks,

I’m about to build a bigger VU-meter using the LM3915.

The IC has open collector outputs which can sink 30 mA max. I need 120mA per output.

first Idea: 4009 inverting buffers (with pullup reistors) and some ULN2803 (or 2804) driver ICs. But I guess, that’s pretty hardcore.

second Idea: would a simple PNP-transistor per output work? Any Idea, which type would be suitable for 120mA@5V ?

thanks in advance.

2

hi folks,

I’m about to build a bigger VU-meter using the LM3915.

The IC has open collector outputs which can sink 30 mA max. I need 120mA per output.

first Idea: 4009 inverting buffers (with pullup reistors) and some ULN2803 (or 2804) driver ICs. But I guess, that’s pretty hardcore.

second Idea: would a simple PNP-transistor per output work? Any Idea, which type would be suitable for 120mA@5V ?

thanks in advance.

I prefer a PNP-transistor type BD136 or similar

Regards,

Janis

[BD136.pdf](< base_url >/applications/core/interface/file/attachment.php?id=7545)

3

The LM 3915 outputs will drive solid state relays. We once built some 3 metre tall VU meters for a night club, using mains bulbs. Later version added lamp pre-heat, (basically a small dimmer feeding a little current into each lamp to warm the filaments, and reduce fatigue failure).

On the same tack, using filament heating transformers, you can build 7 segment displays from fluorescent tubes. 4 metre high digital clock, anyone?