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Posts posted by japroach

  1. It sounds like you are describing the 4 pin molex connector.

    The two black wires in the middle are ground, and you should read voltages with your negative lead connected to them.

    The negative voltages supplied by your power supply are -5 and -12V, and they will connect to your motherboard only.

    All the grounds are connected together, and the negative and positive voltages are referenced from them.

  2. ok i'll try to hold my breath but i can't afford a temp controlled iron :(

    Just get an adjustable one they are maybe 20-40$..

    Or you can use a light dimmer to reduce the power going into your soldering iron.

    I set a fan next to where Im working, if I dont the fumes rise straight into my mouth and eyes.

    Open any windows and doors in the room as well.

  3. ok thanks but for the project i started i'll have to find a way yse a perf bord just have tons of holes and a little coper "O" around the ring

    Yeah there are no connections on the board, those are just places to solder your component leads.

    What you do is place the two wires in two holes close to each other, and make a solder bridge, or just bend one of the wires over a little to make it easier. And if they arent close then you can use some wire on top of the board to connect two points.

    Here is the only decent example picture I could find:

    I think the only reason hes using the large copper wires below is the power in the circuit. Not needed on normal boards.

    btw I use these boards a lot, its very easy to wire up a schematic.

  4. V is the supply voltage.
    Vf is the LED forward voltage drop found on the datasheet.
    I is the forard current - it must be high enough to give reasonable light output but bellow the maximum value listed on the datasheet.

    I dont think thats what hes asking. What hes saying is why use a LED driver chip.

    Main reason is to have constant current output to a bunch of LEDs.

    Most of it explained here:


  5. hi all, i have this idea of circuit simulator where you connect a transistors lead, or any electronics components lead to a computer terminal, and the computer will record its parameters. after that you use thse parameters for simulation. its just an idea...

    For a transistor you can get a curve tracer that will give you a lot of info. For a capacitor/inductor/etc you have to use a freq and check its response at that freq. or do a sweep or something.

    The problem is interfacing with the computer. There is a box you can build to measure inductance, capacitance, and freq sweeps of a speaker.

    But Im not sure if you can import all this info into the circuit simulator. Sure you can put in transistor gain and diode drop (probably), but not everything.

    Good idea though.

  6. The meter won't blow if you short its supply? But I am pretty sure that is what happened.

    The negative power wire came loose and touched the positive connection. Meter will now only read -1 on display. Maybe it also touched something else or something else went wrong. Whatever, meter is now not working.

    I will look again and see if I can find some other problem though. I may have had some other connection wrong also, as I was doing this late at night and was pretty tired.

    New meter is on the way and will be here next week, will just have to play with something else until then.

    Did you check if theres a fuse inside that you can replace?

  7. I have another tip for everyone. If there is a part that isn't a sample, you can usually perform a "escalation" where you can get more expensive parts if you can justify why you need the part pretty well. I got a DSP that way because I said the microcontrollers I used here insufficient for the task I was doing (I had more detail than that, but you get the picture). It doesn't always work and also probably depends on your country. Also, some companies that don't offer samples (on their site) will if you plead your case to them. Especially students because if a student looks favourably on the company, one day he will be buying parts for his company.

    Now, all I need is a place to get free sockets, capacitors, and resistors!

    Yeah I agree.. in the future you make be making parts decisions for your company. And if they have been kind to you in the past, you tend to favor them..  :)

    btw National stopped sending samples to all free/ISP/and school emails that I have. I would gladly pay the shipping, but they want shipping for EACH IC sample.. so thats like 16$ if I want some + and - regulators or something...

    btw stuff like sockets, caps, resistors its easier to buy surplus. Check ebay or locally, you can get then for pennies. But there was one place that had nice socket samples, if you email me I can go find the site. (thomas997 at hotmail.com).
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