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    What to uses as an antenna for rf module

    I am playing around with these RF modules I got off Ebay. These: http://www.ebay.com/itm/IC2272-315MH...IAAOSwxg5XyAmv Ebay item #401183214030 are 315 MHZ. I tried a 1 foot 22 solid copper wire wound around a plain pencil, then hung loose, coiled length about 2 inches ... and that worked...
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    How to detect very high frequency sound ?

    I need some advice on how I might accomplish the detection of very high frequency sound. I do not know the source of the sound, or where is comes from (I don't care and can not answer any questions about that). I also do not know the exact frequency - or range. I know it is higher then what I...
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    ISP Download to DS89C450 using MAX3232 ?

    I'm looking for advice on what I might do to get some RS232 modules I bought to work with my DS89C450 circuit. I bought a variety of RS232 modules off of Ebay, and the ones that use the MAX232CSE work fine. The ones that use the MAX3232ESE do not work completely. All modules allow me to...
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    Solderless breadboards ?

    I am interested in buying some more solderless breadboards. I am only interested in plain simple boards, such as that pictured below - the "Archer Experimenter", #276-174, from Radio Shack. I have not tried the $18 board they sell now. (Imagine an image here uploaded direct from my PC ...
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    3.6v i2C part in a 5V uP circuit

    I wish to use a part the has a max vcc of 3.6 volt, and it's i2c bus in a simple 8051 (DS89C450) circuit. I don't know what the exact 3.6v part is yet - it just seems all the parts I've looked at for my application have a max vcc of 3.6v. I haven't yet read anything in any datasheet that...
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    Looking for 8051 PCB for projects

    I frequently throw together little 8051 projects, always starting out on solder-less bread boards. I get annoyed that I'm always creating the same basic 8051 circuit, then building off of that. I use the DS89C450 (I have dozens), so my base circuit always has the micro, a 74125, a max232 of...
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    Looking for fast camera type flash circuit/module

    I am working on a project where I'd want to generate a flash of light ... and if not too much more of a hassle, perhaps repeatedly, and in rapid succession. It would be for a project that's likely to be in my car (not running) - and could make use of the car battery. I'd like something that I...
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    Miniture power supplies ?

    I frequently do little projects where I want a cheap and small power supply to give me +12v or for some projects just +5v. A few weeks ago while plugging my cell phone into a 120v charger, it occurred to me ... the charger I used with my phone supposedly puts out up to 2 amps at +5v, and has a...
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    Testing car battery

    I am working on a project that requires 12VDC and at least 20 Amps - for maybe 20 seconds, three times a day. The idea of using a used car battery occurred to me. If I look to by a used one, how should I test it ? If I go this route, would it be fine to trickle charge it continuously -...
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    Battery powered device question

    I have a small sealed device that has a USB interface and runs off an internal rechargable battery when not connected to a USB port. I'd like to add an external 9V battery to extend it's life before a recharge is needed. I attached a 9 V battery to a 78L05, and then the 5 V output to the USB...
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    What range of frequencies would do this ?

    What range of frequencies would a "sound" wave have to be to travel easily through a homes outside walls, throughout the inside of the home (through internal walls) and produce a "sound" that is NOT heard, but causes a popping sensation in a persons ears ? Ear plugs, noise canceling headphones...
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    Max232 Type Rs232 Chips - What Type Of Capacitors, MAX232 Charge pump capacitors

    I am building a project using a type of RS232 level translator that runs on just +5 Vdc. The actual part is a Sipex/Exar SP207HCP, but I guess my question would apply to any similar IC that use charge pumps to build up the RS232 level voltages. My Question is, must I used polarized capacitors...
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    IR Project - Viewsonic Monitor drives IR module nuts

    I've worked with IR projects for years. My last one, about 8 years ago, used an Atmel AT89S8252. I just started another one - using a Dallas 89C450. Anyways, my troubles now are not micro-controller related - but IR related. I just wired up my project and the IR output of my IR module, a...
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    What is the part number for a 2 gate 74xx125 - used with Dallas 8051s

    I am building a small foot print board using the Dallas DS89C450. I want to use a 74HC125 (or 74AC125) in the serial programming circuit, but don't want to use a 14 pin DIP. I'd like to use surface mount version - and I believe one exists with just one or two gates to it. Does anyone know...
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    Piezo as glass vibration sensor

    I want to build a little circuit to detect vibration of the glass in a window pane. I was told that a Piezo may help. Can anyone suggest what general parameters of a piezo I should look for in buying some for this application ?
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    DS89C450 In Circuit Programming

    Does anyone know how to obtain a copy of the Dallas MTK software that actually supports the DS89C450 ? Dallas does not know, and the version they offer on their website is 12 years old and does not support the DS89C450.
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    Need help with capacitor markings

    Someone gave me a bunch of capacitors ... but I have no idea what their values are - let alone any other parameters about them ... they got them from where they used to work and can't help me. I'd like to find out the exact manufactures part numbers so I can get full specs on them. If that's...
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    Looking for LED specs

    I need technical data on a series of LEDs made by Kingbright (Kingbrite ??). I believe they are frmo a LED series known as "L193", and have part numbers like L193IDTNR254-21. I would really appreciate getting an original datasheet. I want to know more then forward voltage drop or...
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    Looking For Data On Dreefs Rocker Switch, Looking for data sheet

    I am looking for a technical datasheet on a Dreefs rocker switch. I took some pictures of it ... and put them here: http://www.8051bits.com/dreef-switch.jpg (might be bigger then one below) It has all sorts of numbers on it, inlcuding 2215/1 2Wi11 WZ9 T100 T125 KZ18 I...
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    Looking for ideas for electronic dog whistle

    I want to build an electronic dog whistle that I can fire off for a second or two after the neighbors dog begins it's nightly barking spree. I know it would have to be around 25KHZ ... but am not sure what to try .... piezos ? Any ideas ?
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