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  1. K

    Laser Driver Troubleshooting?

    The circuit you posted regulates current, not voltage. This is what you need for a laser diode, but measuring the voltage across it while open-circuit won't give you the expected results. Connect a load across the output (such as a 10 ohm resistor) and measure the current (in series with the...
  2. K

    LED 1.5Vfd???

    You can dim a blue LED, you just have to reduce the current even lower than the 6-10 mA range. Since blue LEDs tend to be blindingly bright at rated current, you'll want to use a small fraction to make it dim. Maybe 1-2 mA. PWM is the way to go if you need variable brightness, but just to dim...
  3. K

    LED 1.5Vfd???

    I wouldn't think a power LED would be PWM controlled, unless the device makes the LED dimmable, which would solve your problem right then and there. Most power LEDs are simply across the power rails with a current limiting resistor. Also, PWM usually comes from a microcontroller or other...
  4. K

    RAM simulation using Multisim

    Someone might ask why you're not using A8-A10. If it's just a conceptual circuit drawing for homework, why not have all 11 bits of the address on BUS2? Is there a requirement that you only use 256 bytes of RAM? Might as well let the microcontroller use all of it. :) Other than that it looks...
  5. K

    RAM simulation using Multisim

    Long story short, the address you give the RAM is a combination of row and column. The address you provide to the RAM is a certain number of bits depending on the size of the RAM. For a 2K RAM, it's 11 bits. For a 256 byte RAM, it's 8 bits. These bits are divided up to make the row and...
  6. K

    pic16f877a not responding

    There's only a single if statement under the while, so curly brackets under the while aren't needed in this case. It is cleaner looking to use them though. Ditto what others have said, start with a simple program that flashes an LED, then go from there. Also, what do you have the...
  7. K

    Are PICs still being used

    One thing I like about PICs is, for a given pin count, many of them have the same pinouts. I've had a couple one-off projects where I used a lower-end PIC I had on hand, then down the road decided I needed a faster one or some peripheral the chip I was using didn't have. In both cases I found...
  8. K

    Roland xp-50 keyboard problem

    Did you measure it both ways? It's made of diodes, a continuity test will only show continuity in one direction. :) But, if that was the problem, cool, you fixed it!
  9. K

    Magnetic Encoder PINS for a standard use

    The CLK pin is used to clock the serial output. So, you'll need to use this pin if you're using the serial interface. Your dsPIC would provide this signal and would receive the data via the DO pin. You won't need to use these if you're using the PWM output instead. You only need the PDIO pin...
  10. K

    Basic concepts PCB building and dsPIC

    Study the datasheet, especially the parts about what connections are required. In addition to an ICSP header to connect a programmer, many PICs have multiple Vdd and Vss pins that have to be connected to the power rails (and if multiple Vdd and Vss pins are provided, they all should be...
  11. K

    MOSFET Resistance Problem

    When you use your multimeter to measure across drain and source, it's applying a voltage (from the meter's battery) and then measuring how much current flows. If no current flows, it shows an infinite resistance. If current flows, the "resistance" is calculated based on that. The body diode...
  12. K

    iPod as oscillator for scope wave learning?

    As an alternative to using an iPod and tone files, you could run a software tone generator or software synthesizer on a computer, tablet, or smartphone (or iPod if it's a Touch). Then you can generate different waveforms, change the frequency, and add filtering. Just connect the headphone...
  13. K

    Identifying transistor's PINs (Emitter and Collector)

    Did you mean to say the BE junction will break down at a much lower voltage than the BC junction? If you limit the current to a few microamps with a resistor, driving the B-E junction into breakdown shouldn't cause any damage for testing purposes.
  14. K

    MOSFET Resistance Problem

    You're seeing the effect of the MOSFET "body diode". The construction of the FET causes it to act as if a reverse biased diode exists across the source and drain. So, if you measure the FET in the "correct" polarity (drain-to-source voltage positive for N-channel, or negative for P-channel)...
  15. K

    Create Memory/RAM

    You can bake a cake by growing wheat, making flour, growing sugar cane, raising chickens for the eggs, etc. Or build a house by growing a bunch of trees. You could make a RAM from transistors too, but it would be complex and unwieldy. Read up on the history of computers, and read about...
  16. K

    Micro soldering

    A fine tip on the soldering iron, fine gauge solder, and a magnifier are the bare minimum.
  17. K

    How to wire this switch

    I found a manual for the CMP12 charge controller here: http://www.elvet.co.rs/Solarni kontroler 3 KEMO.pdf It doesn't switch the load on/off based on light level, it only cuts power if the battery charge gets low. The OP wants the LEDs to only go on at night, so the photo sensor he's using is...
  18. K

    How to wire this switch

    You're right, that should be terminal 6. My goof. The photo sensor uses AC mains color convention, where black = hot and white = neutral, even though it's designed for 12V. Maybe because it's compatible with 12V AC or DC so it's not polarity, but identifying which wire is common.
  19. K

    Wifi webserver

    The datasheet and documentation should explain how to set it up to connect to (or create) a WiFi network. To make it a server, you just need to have it "listen" for connections on a TCP port, such as 80 for a webserver. If more than one device connects, they will be separate TCP connections...
  20. K

    Wifi webserver

    Looking at the RN-171XV on the web, I see: "Onboard TCP/IP stack includes DHCP, UDP, DNS, ARP, ICMP, HTTP client, FTP client and TCP". You would have to implement an HTTP server. The basic protocol isn't that complicated, it just accepts a connection from a client (browser) which sends a...
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