These bargraph displays were the rage in the 80s. I remember buying the Mosfet amp kits from Maplin's in Hammersmith and adding a pair of these for power output indication. There is also a LM3916 with VU meter levels.
Funny. I bought one of these kits back in October and for some strange reason it did not arrive until January. Also I have been unable to put the kit together as I was also waiting on the mail to deliver some soldering iron tips that I could not purchase at a local store in my home town. Glad I can see it put together before I put mine together.
i like this video VERY MUCH because, as a broadcast engineer, I have seen bar graph representations used in many different ways. One of my favorites is the setups which divide the audio spectrum into many different parts, frequency bands, and have a bar graph for each. Much time was used to make them truly representative of the spectrum. Then, one engineer would take a special type of noise generator and would show representations of the flatness of various parts of the system, including microphones and other parts. He was spending most of his time with FM stations. So, with about 10 of these you could build such a device.
I bought a couple of the raw chips for $1 awhile, pretty simple schematic depending how much control you want and easy to build on a prototyping board. The wiring can be tedious is the only tricky bit, as you need a connection per-LED.
I always found this projects fun connecting them to the HDD activity LED and the LED activity of my Network card. This was a day when I was into PC case modding.
The reason for the resistor on the red LED's is that they typically have a lower forward voltage and so would consequently be brighter at the same voltage as the yellow ones. BTW - Just go ahead and calibrate your sodding component tester!
Dear Sir, I used to watch the video you put on the net! You are a great expert and I am an old retired! I bought two cheap kits and put them together! Go, yes it goes but it doesn't respond to the two channels as it should! The vibrations of the LEDs make it impossible to look at the delays between the channels! It's like a mono! I saw an assembled version in Italian, replaced with the two capacitor electrolyte. But neither drawing nor understanding! An old reader's suggestion to put two 2.2 micro F electrolyte condensers after 5pin, think one channel and solve the vibration and speed! I'm not drawing because they didn't give me an old man just begging! I'd like to thank you for having a line! All the best!
I had built some stuff using these chips years ago, and was contemplating building some more, and when I saw the astoundingly low price on that ebay listing, I went there. Prices were a *lot* higher! Then I added the word "kit" to my search, and got some that were much more reasonable, though still a little higher than what I saw in the video. There are also versions of this which have a 741 op amp on the board, presumably to provide that rectifier function. I know that when I came up with my original circuit for this, years ago, I had to use an op amp and some filtering to get the "dot mode" display to work like I thought it should...
I'm glad you made this. I thought about buying the kit, but I have all the other stuff so I just bought the chips. Especially since you pointed out that it needs a rectifier for a full AC wave.....Plus I have some RGB LEDs and I might come up with something that looks innovative, yet still makes sense .....
I bought exactly the same kit from aliexpress with hope to use it as a battery voltage indicator. I was hoping (without reading manuals of course) that it'll work in a wide range of voltages: from ~3 to 15 volts. so I could use the battery itself as a power source for the IC. It turns out, that it's not gonna work that way. But I still can use a 9V battery as a power supply for IC and maybe replace LM3915 with LM3914 to achieve the goal. Thank you very much for the video!
Some interesting for builder followers of Julian, like me. You can swap out the LM3915 (log Chip) for the LM3914 and get a linear response which might better suit your particular requirement. There is even an LM3916 too.
It will be very interesting to see your final version. I'd be impressed if it has the true characteristics of a PPM - rapid attack response and a very slow release. Or will it be a simple peak indication?
I messed with those chips back in the day a lot. You can alter the response of the LED's by paralleling resistance to ground on the input pin. You'll end up having to increase the gain on the input, but it tended to increase the "turn on/off" voltage sensitivity between the individual LED's and it would make it less likely for 2 to be on at the same time. It was a different application so I'm unsure what effect it would have on audio.
You really need to calibrate your Transistor Tester. Just short out pin 1-2-3, long press. Unconnect the shorting cables when your told to, and stick in a >100nF low ESR capacitor (film is good) when the C-1 test shows.
simply exchange the LM3915 with the 3914 for lineqar...oh you just said it...and the ´16 makes a fully true VU meter...;) I love these chips...you can do so many great things with them...i used it so many times in my designs....over and over again... The original TI-datasheets are somewhat complete, comprehensive and totally worth reading...:) Great chips....;) Well Done TexasInstruments. You may add a peak rectifier on top of that precision rectifier...so it will show both at a time...in dot mode...also read the data sheet where the current limitation is explained...you can drive the LEDs with far more current in dot mode hence brighter lights ;)
Domino : I don't know of any benefit of more than 6V. I didn't build this kit BUT did build a similar circuit for a VU Meter project I built. I currently am using a 9V adapter I had around. Here's my link if you care to view.....ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-afNoje0KEFI.html
Thank you Julian, I bought one of these kits and was not happy about it, but after watching this clip I will be changing the 50k around and also I was thinking of taking the 2-1K res and replacing with 510R just so as I can get the reds to light up more, the other thing I am wondering about is the audio input, should that be from line out or speaker out from amp, thanks
nice video... two circuits of two lm3914 (4) chips should make a sweet on pcb pos/neg 10vdc linear signal input/output setup meters... with dots or bars for power saving? Thanks...:)
But Julian, you should have used darker yellow LEDs and keep it flickering for vintage looks! If you dont have dark yellow ones used RGB LEDs and solder resistors to the pins so you get an orange color! And don't tell us that thats overkill, its called turn "$%#T into gold" :D
I can’t get dot mode, 9v to pin 9 is blinding bright bar mode, GND to pin 9 is bar mode with both end leds always on, unconnected is best it’s not as bright bar mode
Ok, I know this is a bit random but: At 10:43 julian's phone has that same bing bong noise that big clive's has. Is that from a specific app on your phone or is it a standard notification sound that android uses??? I really need to know. Sorry for the silliness over a noise XD
I just thought, you could use that wonky dot mode. stick this vertically and wave it around to make the worlds worst digital oscilloscope. might even make some interesting long exposure / double exposure photographs... like a sine wave going through your head.
I have. i would recommend GreatScott's instrucatble, it provides the basic knowledge needed to get started along with some example code for the arduino. www.instructables.com/id/How-to-build-your-own-LED-Color-Organ-Arduino-MSGE/?ALLSTEPS
