This circuit is a DIY mini TV / monitor with LED matrix, it takes the video signal and display it on 80 LEDs.
Although the video has very low resolution, but it is very interesting as an educational project !
I call it Stone Age Monitor 😁
It can be used for decoration and also for Local dimming backlight projects for small size LCDs.
Parts list:
IC LM3914 (2pcs)
IC AD8032 (SMD or THT)
IC LM1881 (SMD or THT)
Resistor 1K 0.25 Watt (3pcs)
Resistor 120 ohm 0.5 Watt
Resistor 180 ohm 0.25 Watt
Resistor 390 ohm 0.25 Watt
Resistor 510 ohm 0.25 Watt
Resistor 680 ohm 0.25 Watt
Resistor 2.2K ohm 0.25 Watt (3pcs)
Resistor 3.3K ohm 0.25 Watt (3pcs)
Resistor 4.7K ohm 0.25 Watt
Resistor 5.6K ohm 0.25 Watt
Resistor 6.8K ohm 0.25 Watt (2pcs)
Resistor 68K ohm 0.25 Watt (2pcs)
Resistor 680K ohm 0.25 Watt
Capacitor 220uF 16V
Ceramic capacitor 100nF (4pcs)
Ceramic capacitor 22nF
Ceramic capacitor 10nF
Diode 1N4148 (2pcs)
Slide Switch 3 pin
Transistor 2N2222 (5pcs)
Transistor 2N5404 (8pcs)
Transistor 2N3906 (2pcs)
BNC Female PCB Connector
3mm LED (80 pcs)
Multiturn Potentiometer 10K model 3296 (5pcs)
Multiturn Potentiometer 1K model 3296
IC Socket 18 DIP (2pcs)
IC Socket 8 DIP (2pcs)
9V Battery with holder / cable
Circuit:
You have to preset the potentiometers otherwise the circuit will not work.
Pay attention to the voltages written on center pin of each potentiometer connected to pin4 and pin6 of both IC LM3914, To achieve the best result turn the knob until you get those voltages with respect to the ground (negative side of the battery).
This circuit draw 120 mA of current from the 9v battery which can drain the battery very quickly, so its better to use a 9v adapter instead.
I didn't used any current limiting resistor for the LEDs and base of the transistors because IC LM3914 has a constant current LED driver build in.
All resistors are 0.25 watt, except the 120 ohm is 0.5 watt.
Download the Gerber file of this PCB from here:
https://drive.google.com/file/d/1WY7ew1Mi5WgT22n09vgNYxsGwbKBvnpC/view?usp=sharing
Watch this Video for more details: