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Wednesday, Oct 21
4x4 Matrix Keypad PIC18F6520
MOVLW 1 // Moves current 1 to W (not address) OUTPUT: CALL L0, 0 CALL L1, 0 CALL L2, 0 CALL L3, 0 CALL L4, 0 CALL L5, 0 CALL L6, 0 CALL L7, 0 CALL L8, 0 CALL L9, 0 CALL LA, 0 CALL LB, 0 CALL LC, 0 CALL LD, 0 CALL LLE, 0 CALL LF, 0 RETURN 0 RETURN 0 // Return BSF LTA, A, ACCESS BSF LTB, B, ACCESS BSF LTC, C, ACCESS
Wednesday, Oct 14
Bad LED
I concluded it MUST be a bad diode because it was from 5 volt bus to ground bus across all 15 RED LEDs, and the suspect LED was the only one showing an odd voltage (3.1 volts instead of 4) Knowing that CMOS logic requires a threshold voltage to change states, I figured the CPU wasn't happy with 3.1 v...
Sunday, Sep 27
How To: Current Meter LED Bar Graph
So, 0-99mA will light 1 LED. 100-199mA will light 2 LED's and so on. I was thinking of using the LM3914 to drive the LED's, but this means I need to convert the Current to a Voltage. So, I was thinking of using this part; ASC712 Hall Effect Current Sensor
Thursday, Sep 24
LEDs and powering 'em
I am trying to come to terms with LEDs and power supplies. Goals: To learn how to build and to power LED arrays & do it. To learn about the relationship between power supplies and LED power consumption. To learn how to build my own power supply. There is an Wikihow article on turning a PC power s...
Friday, Sep 4
a few questions about Digital Step-Km Counter circuit/help
R1,R3____22K 1/4W Resistor R2________2M2 1/4W Resistor R4________1M 1/4W Resistor R5,R7,R8__4K7 1/4W Resistor R6_______47R 1/4W Resistor R9________1K 1/4W Resistor SW1______SPST Mercury Switch, called also Tilt Switch
Wednesday, Aug 26
op-amp triangle wave, need help
I've tried adjusting the values of the components and the best I can get the circuit to do is to make the LED fade on, put after that it just gets stuck on and doesn't fade back off. To do this I changed out the resistor that goes from pin 7 to ground from a 4.7k Ohm to a 1k Ohm.
Tuesday, Aug 25
Opinion: Sizing a Solar Panel & Battery for an LED Light
I have a 12 volt, 10 LED light that I would like to hook up to a battery & solar charger with a photocell switch so that the light will come on at night and shut off during the day. The current draw for the light is .08 Amps. So 12 volts X .08 Amps = .96 Watts
Saturday, Aug 22
Automotive LED Driver Help
It is the LT3755 IC. In the datasheet, it has a typical applications section. One of the examples is a 50 watt automotive LED driver. It gives a schematic but that is about it. The example can be found on page 18. It is a typical schematic that labels parts as D1, M1, etc. It gives part numbers for these...
Friday, Aug 14
LED VU Meter 101
Resistor RD affects the dot sweep rate: less resistance makes it sweep faster. This can be user adjusted based on preference. The LM3914 dot select pin is left open to select single LED (dot) mode, but in reality, about four or five LEDs are lit at any one time as the thing sweeps the display wit...
Saturday, Aug 8
teach old dog new LED tricks
On the left of the relay (as you look at it.) is a simple constant current LED driver circuit. On the right is the fan itis 12v 1.5amp. The relay is DPDT. I am running both the LED circuit and the fan from the same supply and I wanted to be able to adjust the fan input hence the constant current LED circui...
Monday, Jul 13
Not enough power reaching IR LED
The circuit seems to work with the transmitter and receiver in close proximity, and with no damage to the IR LED, but I inserted an ammeter between R3 and L1 to check whether the current reaching the IR LED is as high as desired, to make sure that the 90% mark-time wave was indeed protecting th...
Saturday, Jun 27
Intermediate 5W voltage-controller LED Current Driver
Here is a voltage-controller LED current driver for those who are not afraid to burn some POWER! Forget those wussy switching things trying to achieve, what?, 85% efficiency maybe? What a hassle. Attached Thumbnails Here is a voltage-controller LED current driver for those who are n...
Saturday, Jun 20
Timed Robot/Circuit - NEED A CIRCUIT TO TURN LED ON AND OFF AT SPECIFIC INTERVALS
For the sake of simplicity, I am testing with LEDs right now and if my circuit works then I will just change the LEDs with relays connected to motors, I can use both normal relays and latching relays (which only need a pulse to turn on or off).
Friday, May 29
Shifting(74LS164) is not working!!
I am currently working on LED dot matrix display by using 16F877A and 74LS164 shift register to shift the data that out from 877A..I face a few problem while doing the shifting.. 2)First data that i sent in , light on all the time and there's no shifting that can be seen on the matrix display.
Tuesday, Apr 28
Light a different LED with changing A/D input
Is there an easy way to light one LED when the ADC reads a certain value on the input, light first and second LEDs when a higher level is reached and light three LEDs in the last part of the ADC? I've managed to get it to read the ADC but it only lights the LED when it is exactly one value and not above...
Thursday, Apr 16
Bicycle dynamo LED - adding a "super cap" to keep it lighted ( after stopping )
Dynamo LED Light Systems for Bicycles (electronic circuits) So ! Dynamo LED Light Systems for Bicycles (electronic circuits) So ! DealExtreme: $6.90 9-LED Bike Head Light (3xAA) Dynamo LED Light Systems for Bicycles (electronic circuits)
Tuesday, Apr 14
Preventing a voltage source from stealing from AA batteries
If I touch the two wires on the battery, it's super bright. Measuring the DC voltage between the two LED pins, I'm getting 2.8v to the LED. Here's where my problem comes in: When I connect the "idiot light" to the MAF sensor, the LED lights up EXTREMELY dim, so dim that you can't really see it at all...
Wednesday, Apr 8
Looking for recommendation of LED driver with individual LED PWM control
Lighting and Display Solutions - LED Drivers - TLC59116 - TI.com I am concerned that this chip can only connect up to (14) I2C TLC59116 chips. That is only 14 X 16 outputs or 224 LEDs. How would I get around this? I need to have 1000's of LEDs in 16x8 modules driven by a 'smart' PWM LED driver.
Thursday, Apr 2
LED Matrix Questions
So, my first concern is whether I should try to put 8 LEDs in series as the wizard suggests since I may have variations in Vf, or have lower than 12V source due to ripple, current demands, variations in different wall warts (I have one that's rated at 12V, but only gives me 10.5V), etc. Would it be...
Wednesday, Mar 11
How To: Astable then steady
I try to build an auxiliary LED brake light driver to my bike using a basic 555 astable circuit. I want it to flash 3-4 times in the first second when the brake applied then hold a steady light until I release the brake. Any idea how to achive this?:confused:
Sunday, Jan 25
befuddled
The circuit on the left on the attached figure is a low voltage light flasher as I transcribed it from DAVE JOHNSON’s UNDER VOLTAGE LED FLASHER ( Low Power Under-Voltage LED Flasher - Circuit Description and http://www.discovercircuits.com/PDF-FILES/undervol.pdf ). C2 was changed from...
Saturday, Jan 24
Inverter to make 110v LEDs NOT flicker?
OK, so But I don't think I'd want to put a rectifier bridge on the "mains" directly - well, maybe through a fuse? Fuse Bridge Feed to a pair of ?? (advice sought) MosFets, producing an output square wave Feed the (400Hz?) square wave to an outlet, clearly labeled "for LED Rope use only".
Monday, Dec 29
Unique LED light chaser questions, w/ schematic
Can I use just one resistor for each group of LEDs (R7, R8 and R9) instead of one for each of the six branches in the LED groups? If I need a resistor for each branch (of three LEDs), I have calculated them to be at 75Ω each. R = (1.8 volts dropped / 0.024 Amps) = 75Ω
Sunday, Dec 21
Advice on writting a report
The speed of each is left to you to assign. The clock should keep running accurate even in case of power off state ( by the aid of internal rechargeable battery or any alternatives ( suggest!) The power is supplied through a 12V DC power supply ( a transformer (220/12) with AC/DC converter on t...
Friday, Nov 21
Solar Powered Japanese Garden Lantern Advice
I would rather use / adapt the solar cell - battery charger i have than purchasing a 12V [15.4V] new unit, as these can cost rather a lot for such a small circuit. I am also open to the idea of changing my resistors in the Xmas light kit, so i can halve the LED output, as this would still give enough li...
