i need working lm3915 schematic with have dot/bar mode switch because all i finded in comments pople write about problems, found this one LED Audio VU Meter but its supplyed by 20v single supply i need it to work from 12-15v single supply and does it work like in this video LM3915 led dot/line mode - YouTube one switch controls mode 😕
Look on the data sheet.
All the information is there.
That is what I designed mine from.
You can run them from a 5V supply.
🙂
All the information is there.
That is what I designed mine from.
You can run them from a 5V supply.
🙂
I second the datasheet. National datasheets from that era did everything but send someone to build the circuit for you. You'll find everything you need on the datasheet.
1. lm3915 is 3dB/step (lm3914 is linear)
2. Fig 39: http://www.ti.com/lit/ds/symlink/lm3915.pdf
3. "...i find out comments saying that datasheet shematic just always light for them not blinked along music " I am not sure what you mean or what these comments mean.
2. Fig 39: http://www.ti.com/lit/ds/symlink/lm3915.pdf
3. "...i find out comments saying that datasheet shematic just always light for them not blinked along music " I am not sure what you mean or what these comments mean.
Thanks all, for the original question and for the answers. Got myself a project now instead of just browsing ebay.
And how about this schematic Zippyshare.com it was used in this video: Vumetro estereo con LM3915 (DIY) - YouTube but instead of 12v i supply the chip with 14.5v and use 120ohms resistor insted of 100 to drop voltage for leds down to 3v (because datasheet says that voltage for leds must be lower than 7v for dot mode) but chip gets same 14.5v and then i make switch from pin 3 to pin 9 put potentiometer in signal's way and one cap to ground how about it?
Read what the data sheet says about the function of each resistor.
You could drop the LED supply down with a zener. Then dot or bar mode would not matter to loading...Or use a regulator.
It looks like you are starting to understand the circuit.
It is what DIYing is all about.
🙂
You could drop the LED supply down with a zener. Then dot or bar mode would not matter to loading...Or use a regulator.
It looks like you are starting to understand the circuit.
It is what DIYing is all about.
🙂
i've done lm3915 vu meter by this schematic http://i.imgur.com/r5NgGyo.png but dot mode seems to be not working then i disconect wire from pin 3 to pin 9. then i disconect it led's seems to light not that bright as in bar mode but its still works in bar mode.What could be the problem? 😕 and the 100ohms resistor is connected only from power supply to leds + but chip gets raw 12v of supply, not after 100ohms resistor maybe that is the problem?
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connecting 100ohms resistor like in diagram not make any diference, it still works in bar mode even then pin 9 is disconnected from vcc (pin3)
The problem with this circuit is that the designer does not seem to understand what the external resistors do.
http://i.imgur.com/r5NgGyo.png
There is an internal adjustable 1.2V regulator that is used to set two things.
1. LED current
2. reference voltage for full scale
Look at the 6th page of the data sheet!
http://www.ti.com/lit/ds/symlink/lm3915.pdf
By using the 220R and 2k2 that way the LED current is set for 1.2V / 220R
Nothing wrong with the 220R...about 5.4mA
BUT the 2k2 would set the Reference at about 13.2V.
Not exactly possible with a 12V supply.
Change the 2k2 to a 1k0 and then check the circuit's operation.
(And put a 8V zener in the LED supply line for dot mode)
Data sheet.
The manufacturer does know a little about how their product works.
🙂
http://i.imgur.com/r5NgGyo.png
There is an internal adjustable 1.2V regulator that is used to set two things.
1. LED current
2. reference voltage for full scale
Look at the 6th page of the data sheet!
http://www.ti.com/lit/ds/symlink/lm3915.pdf
By using the 220R and 2k2 that way the LED current is set for 1.2V / 220R
Nothing wrong with the 220R...about 5.4mA
BUT the 2k2 would set the Reference at about 13.2V.
Not exactly possible with a 12V supply.
Change the 2k2 to a 1k0 and then check the circuit's operation.
(And put a 8V zener in the LED supply line for dot mode)
Data sheet.
The manufacturer does know a little about how their product works.
🙂
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i plan connecting tis circuit to 14.4v 🙂 i've putted 100Ohms 5W resistor just to be safe that it doesnt heat up that daage itself like 1w can....is it really good to put 8v zener in line with leds witch need 3v? 3v for green and for red i added resistors to leds because red led burn's out at 3v or not if lighted for second,but no more
Please read the data sheet.
A lot of your questions can be answered by doing that.
The voltage drop of the LED's has very little to do with the operation of the circuit.
The 220R sets the current for the LED...end of story.
If your circuit has the pot at the input you can put a 0R in the 2k2 position.
Drop the voltage to the LED's by using a zener.
Putting a bigger resistor in the 100R position because it heats up is not the solution to the circuit's problems...it only fixes the resistor's problem.
A lot of your questions can be answered by doing that.
The voltage drop of the LED's has very little to do with the operation of the circuit.
The 220R sets the current for the LED...end of story.
If your circuit has the pot at the input you can put a 0R in the 2k2 position.
Drop the voltage to the LED's by using a zener.
Putting a bigger resistor in the 100R position because it heats up is not the solution to the circuit's problems...it only fixes the resistor's problem.
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