Long before I published articles in Nuts & Volts / Servo Magazines, I used to publish in late 80s / early 90s computer and electronic magazines. I started doing it under a pseudonym, but later used my real name. While looking for something old online, I came across this article in Popular Electronics from January of 1994 (https://www.worldradiohistory.com/Archive-Poptronics/90s/94/PE-1994-01.pdf) that I submitted. It was a revision to the schematic for the LM3915 to make the level meters look better when displaying an audio signal, which is AC, and therefore causes some weirdness with the input of the LM391x chips. The circuit is old and was later revised to work with line-level signals, rather than speaker outputs.
Nice job, Chris. It took me a bit to find the actual article, but it is on page 25, in the magazine.
Quote from: granz on Sep 09, 2025, 06:43 AMNice job, Chris. It took me a bit to find the actual article, but it is on page 25, in the magazine.
I should have probably added: "Press CTRL-F and type Savage" to get to the article. ;)
Quote from: Chris Savage on Sep 09, 2025, 09:00 AMQuote from: granz on Sep 09, 2025, 06:43 AMNice job, Chris. It took me a bit to find the actual article, but it is on page 25, in the magazine.
I should have probably added: "Press CTRL-F and type Savage" to get to the article. ;)
Hah, I pressed CTRL-F and typed LM391 to get the article.
I did notice that that issue had some articles on weather station equipment (my new project - https://savagechats.com/index.php?topic=457.0 (https://savagechats.com/index.php?topic=457.0).) However, when I went to the first article ("Build a Portable Barometer, pg 31) it turned out that the person who scanned the magazine put that page in upside down. >:(
Quote from: Chris Savage on Sep 08, 2025, 11:22 PMLong before I published articles in Nuts & Volts / Servo Magazines, I used to publish in late 80s / early 90s computer and electronic magazines. I started doing it under a pseudonym, but later used my real name. While looking for something old online, I came across this article in Popular Electronics from January of 1994 (https://www.worldradiohistory.com/Archive-Poptronics/90s/94/PE-1994-01.pdf) that I submitted. It was a revision to the schematic for the LM3915 to make the level meters look better when displaying an audio signal, which is AC, and therefore causes some weirdness with the input of the LM391x chips. The circuit is old and was later revised to work with line-level signals, rather than speaker outputs.
Took while to find, but found it. Sad those chips are history now..
Quote from: JKnightandKARR on Sep 09, 2025, 10:54 AMTook while to find, but found it. Sad those chips are history now..
I'm not sure what you mean about them being history, but you can still get hold of them.
Jameco:
https://www.jameco.com/z/LM3915N-1-National-Semiconductor-10-Segment-Dot-Bar-LED-Display-Driver-3dB-Step_901061.html
Digikey:
https://www.digikey.com/en/products/detail/texas-instruments/LM3915N-1-NOPB/305102
A full experimenter's board:
https://www.amazon.com/FTVOGUE-Lm3915-Indicator-Preamplifier-Amplifier/dp/B0B6ZWX828
Quote from: granz on Sep 09, 2025, 11:52 AMI'm not sure what you mean about them being history, but you can still get hold of them.
He's right though...while you can still find some (I found some on Walmart.com!) they're no longer being produced, according to the notification I received several years back. The LM3914, LM3915 and LM3916 are out of production as far as I know. I just checked the manufacturer website (https://www.ti.com/sitesearch/en-us/docs/universalsearch.tsp?langPref=en-US&nr=68&searchTerm=LM3914#q=LM3914) and sure enough, they're listed as obsolete.
Quote from: Chris Savage on Sep 09, 2025, 12:06 PMQuote from: granz on Sep 09, 2025, 11:52 AMI'm not sure what you mean about them being history, but you can still get hold of them.
He's right though...while you can still find some (I found some on Walmart.com!) they're no longer being produced, according to the notification I received several years back. The LM3914, LM3915 and LM3916 are out of production as far as I know. I just checked the manufacturer website (https://www.ti.com/sitesearch/en-us/docs/universalsearch.tsp?langPref=en-US&nr=68&searchTerm=LM3914#q=LM3914) and sure enough, they're listed as obsolete.
Okay, got it. With the term "history" having a few different meanings regarding components, I wanted to make sure that he could still get them if he wanted to play around with your old circuit.
Quote from: Chris Savage on Sep 09, 2025, 12:06 PMQuote from: granz on Sep 09, 2025, 11:52 AMI'm not sure what you mean about them being history, but you can still get hold of them.
He's right though...while you can still find some (I found some on Walmart.com!) they're no longer being produced, according to the notification I received several years back. The LM3914, LM3915 and LM3916 are out of production as far as I know. I just checked the manufacturer website (https://www.ti.com/sitesearch/en-us/docs/universalsearch.tsp?langPref=en-US&nr=68&searchTerm=LM3914#q=LM3914) and sure enough, they're listed as obsolete.
While true, how much longer though?? That's why I am going to try arduino for my voice box kitt/karr project.