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- From: strohm@mksol.dseg.ti.com (john r strohm)
- Subject: Re: chaser lights
- Message-ID: <1992Nov5.154821.28348@mksol.dseg.ti.com>
- Keywords: chaser lights
- Organization: Texas Instruments, Inc
- References: <1992Oct22.143703.6299@sactoh0.sac.ca.us> <1992Oct30.194327.841@phx.mcd.mot.com> <1d8b3mINNgqe@uranium.sto.pdb.sni.de>
- Date: Thu, 5 Nov 1992 15:48:21 GMT
- Lines: 20
-
- RE: construction of chaser light circuits
-
- Everyone so far has proposed a digital approach to the problem. Just to
- be different, there is a fairly simple analog/mixed approach.
-
- National Semiconductor makes three parts: LM3914, LM3915, LM3916. These
- are LED bar-graph controllers. LM3914 has a linear response. (LM3915 has
- a log response, and LM3916 is specifically set up for VU-meter applications.)
-
- These parts basically require an analog voltage input, and you connect up
- a handful of LEDs on the other side. They can be set up for bar-graph or for
- moving-dot (only one LED lit at a time). Radio Shack used to sell them; I don't
- know if they still do.
-
- So the problem becomes one of constructing a suitable analog waveform and
- gluing it to the chip. (Note: if you need something other than LEDs for the
- chaser lights, use optocouplers.) There are lots of sources for waveform
- generators out there: you can even get reasonable results from a 555 by
- tapping the high side of the timing capacitor.
-
-