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Re: How to (replace DPCO relays with simple transistros)
Giuliani
开云体育Yes, I have already tested it. Here the
schematic.
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The 4093 sinks only?a few
microamperes.
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Bye.
Giuliano
? ----- Original Message -----
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Re: datasheet
Giuliani
Here you can find an old Motorola data-sheet (4.9MB).
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Bye. Giuliano ----- Original Message -----
From: Roy J. Tellason To: Electronics_101@... Sent: Saturday, April 29, 2006 2:53 AM Subject: [Electronics_101] datasheet Any of you guys have, or know where I can find, a datasheet for the chip MC1358? Got one here, and I'd like to know a bit more of what can be done with it... -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin |
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Business Idea
Hugh O'Brien
Hi
I work as a wireless technology consultant. I have an idea for creating a car/house alarm system that uses wireless technology to alert the user when something is wrong, e.g. their car is stolen. Also allowing the owner to control his car/house remotely, e.g. switch of fuel supply, or turn of lights etc. I think that there is a big market for this. I know alot about the wireless end and software end of things, but not too much about the harware/pherifials/switches side of things. Any one interested. Hugh |
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Re: need help in Power Supply
Tavys Ashcroft
To get 24V DC, you need a transformer which will have a peak (with reference to zero) voltage of just over 24V on the secondary (output). The ammount over depends on whether you're using a two or four diode full-wave rectifier (don't go half wave, you get too much ripple). With the two diode full wave you need a center tapped transformer and the secondary voltage should be about 0.7 volts above what you need (voltage drop across a diode). With a bridge rectifier, you don't need a center tapped transformer and the secondary voltage should be about 1.4 volts above what you need.
I would recommend you get a bridge rectifier. It's essentially four diodes arranged in a ring, within one small package with four pins. You have two pins for AC input and two pins for + and - DC output. I'm sure there's schematics for power supplies all over the internet, so you just need to adjust values to what you need and put them into the schematic you find. There's lots of different ways of setting up filtering and regulation. Basically what you need is a nice big filtering capacitor to remove the AC ripple, and a 24V regulator. You can put both of these in parallel with your DC output. So if you're using a bridge rectifier, you want your secondary peak voltage to be about 25.4 volts, or maybe 26 volts if it's easier to find. But that's peak, not RMS. To convert it, you divide by the square root of two. That's about 17.9 volts RMS. So if you can find a 120V primary / 18V secondary transformer, you should be set. Then you need a regulator and a filter cap. There's some other components, but that's the basics. Look for real schematics online. But I'm no expert here, just a student. I may not yet know enough about power supplies. Test what you get before hooking it up to your fax machine. And make sure you use a regulator, because if not when you test the voltage on something before you hook it up to a load, it will change when you hook it up. -Tavys |
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Need info on Selectronics or other mfr of the SB100 "Sound Bridge" FM transmitter
Ed Miller
Need info on Selectronics or other mfr of the SB100
"Sound Bridge" FM transmitter There used to be a mini FM transmitter made by Selectronics called the "Sound Bridge" model SB100. I would like to know if anyone might have any contact information from that company or the company from whom these units may have been obtained? At one point in time, they were sold by All Electronics and by Parts-Express. I have written to both of these companies with no luck. At some point in time, these units were also given away free to customers ordering a certain CD player or players. If that rings a bell with anyone who might remember which company offered them as a free bonus, that might help me track them down. I'm looking to either order some in quantity, find a company who made them or distributed them, or find a schematic. You can see a photo of this unit at: Thanks very much, William E. Miller, ASEET Chesterfield, Indiana US Need Mfr. Info on SB100 "Sound Bridge" FM Transmitters! See pic @ __________________________________________________ Do You Yahoo!? Yahoo! Auctions - buy the things you want at great prices |
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need help in Power Supply
we have a fax machine that is always busted whenever there's a power
surge,so I suspected that the power supply of the fax machine is not regulated..instead of fixing it I decided to make one. but the problem is all of my notes in electronics only gives me a 20volts DC output which is not enough to supply the fax machine. (it uses a 24vDC output) Does anyone here have a circuit diagram of a regulated 24v Power Supply? I will appreciate any help. Thanks. |
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Re: new one
Thomas Lee Mullins
--- In Electronics_101@y..., reniar@c... wrote:
Hello guys,Have you tried the group? I am a member of more than one group (if one group can not answere a question, perhaps another [of the same type]can?). |
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Re: IC's?
Matt Hill
checkout www.icmaster.com to find who makes the IC.
Then go to the manufacturer website. =] matt hill --- Zach Archer <slander@...> wrote: Oh yeah -- I also got a few IC's in the package. Is __________________________________________________ Do You Yahoo!? Yahoo! Auctions - buy the things you want at great prices |
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multimeters' funcionality testing jig
I need to build a jig using an AC source from outside to see if a
multimeter is functional. Have to design it to be able to test resistance, cap, current both AC and DC, voltage, diodes. Does anybody know where could I find some schematics to help me? Thanks Michael . |
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More transformers...
Zach Archer
I generated low-level AC voltage using a sound program on my computer -- I looped a 60 hz sine wave, and ran it through my mixer for amplification, and then into the transformer. On this side, the voltmeter read 2 volts rms AC. The other side of the transformer read 1/3 of a volt, which would indicate a 1:6 ratio stepping down. BUT...
I tried flipping the transformer around, which ought to have changed its ratio to 6:1, right? And it gave me the same reading, 2 volts in, 1/3 volt out. Hmmm. The other model of transformer (the one with 11 pins) gave me a surprise -- the incoming side read 4 volts rms AC, and I couldn't find any current or voltage whatsoever on the other side. Confusing! Time to search the web, I guess, and see if I can determine more info about these components based on their ID numbers... -- Z |
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Re: Evaluating a transformer?
Zach, try AC voltage, Good Luck, Steve
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At 05:44 PM 5/18/01 -0700, you wrote:
Greetings all, I won a small box of assorted electronic components on |
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Re: IC's?
Tavys Ashcroft
Oh yeah -- I also got a few IC's in the package. Is there a directoryWell, aside from just looking up the part number on google, there's: The Chip Directory and Semiconductor Cross Reference Search Each usefull in a different way. Zach, email me which chips you have and I'll come up with a fun circuit or project for you. -Tavys |
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Re: Evaluating a transformer?
Tavys Ashcroft
Then I'm measuring the DC voltage on both sides.Well there's your problem right there. Transformers only work for AC. It's inductive coupling. As the primary's voltage goes up and down, a magnetic field expands and collapses. This magnetic field's velocity induces voltage in the winds of the secondary, giving your your secondary voltage. When it's only DC, the magnetic field is constant, and so there's no change in the magnetic field to create movement in the electrons. Any ideas? The small transformer got warm, which at least indicatesWell, the warmth is created by the resistance of the wire. It's usually pretty thin gauge wire, which has been dipped in varnish and baked to keep winds from shorting. I make large inductors at work similar to this, but they weigh 300 pounds. Sometimes we 'DC Bake' them. The heat from DC current will cook off any wet varnish solvent inside after we bake them in a large oven. Mmmm Xylene eating my brain cells. So, if you want to evaluate a transformer, you're going to need a sine wave generator. Any AC will do, but a sine wave is a good place to start. Plus, you get to turn the knob and make space sounds. Outer space sounds like someone turning a knob on an oscillator, by the way. Then you use your multimeter in AC mode and measure primary and secondary voltage. The one with five wires is probably center tapped, which means you get full secondary voltage across the two outer wires, but half of that from the center wire to either outer one. Center tapped transformers are usually used in non-bridge full wave rectifier circuits for DC power supplies and such. -Tavys |
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Evaluating a transformer?
Zach Archer
Greetings all, I won a small box of assorted electronic components on eBay, which arrived today. I'm still trying to evaluate + test all of them, but I have a question regarding transformers. The box came with many small transformers, 2 different kinds -- the smaller kind has 5 leads (3 on one side, 2 on the other) and the larger ones have 11 leads (6 and 5).
I'm trying to determine the turns ratio of both models. Unfortunately I'm not having any luck... What I'm doing is setting a variable DC power supply to either 6 or 3 volts, and connecting that to 2 wires on one side of the transformer. On the other side I'm attaching a 5-watt, 100-ohm resistor to a couple leads. (The leads are being chosen semi-randomly...) Then I'm measuring the DC voltage on both sides. The primary side (er, the side with the power supply connected to it... This is another unknown, I'm not sure which side steps the voltage up, and which steps down?..) responds okay, it measures the DC input, minus a few volts. The other side, however, always registers as dead, I'm not measuring any voltage across the resistor at all. Any ideas? The small transformer got warm, which at least indicates that it's doing something, but the large one stays cool... -- Z |
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Re: Thelephone line modulation with tv signal
Barry Hansen
The audio bandwidth over telephone connections is too low to support
full-motion video. However, amateur radio operators have been sending
color pictures over the airwaves using the small audio bandwidth for many
years. This would work just as well over the telephone.
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Read about SSTV (slow scan television) which sends pictures with audio modulation. It fits neatly within a 2.6 kHz bandwidth, and is suitable for telephones and all sorts of audio recordings. Search the Internet for SSTV and you'll get lots of hits, such as this one: To make the pictures fit into audio, each frame takes a few seconds to a couple minutes, depending on the picture's resolution and number of colors. You give up motion, but the pictures are quite nice. Equipment? SSTV can be built quite cheaply using a computer with a sound card. Free software is available from ham radio web sites. There is another alternative, too. If you're going to use a computer anyway, then an ordinary modem connection is better optimized to send data and digital pictures across the phone lines. Good luck, Barry I want to send a video by telephone line, but i dont know how to |
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Re: Thelephone line modulation with tv signal
Tavys Ashcroft
I want to send a video by telephone line, but i dont know how toWell, first you should learn a bit about the nature of a video signal, and the frequency response of telephone systems. The audio in telephones is of a very limited band. Something like 500-3000 Hz (don't quote me on that, I don't actually know it). So what you need is something that can perhaps digitize your video signal. Real analog video signals are at a very high frequency which would never make it across a phone system. With a digital signal, you'd need the sampling rate to be within the audio range of the telephone system, but would otherwise probably not have a problem. The drawback of that is having such a low sampling rate leads to low quality and low frame rate. That's why nobody has a good looking video telephone yet. im lookin for a circuit that modulate the telephone line with aI'm sure it's possible to make..something..but don't count on high quality. The phone system is one of the least reliable systems as far as quality goes. Nearest I can see is some sort of complicated audio range beat frequency type thing but it would probably be next to impossible to make, forgetting the distortion and signal loss over phone lines. You'd be better off going digital. I'm no expert on analog to digital stuff, but I know there are lots of analog to digital chips available. You'd just lose a whole lot of quality for the low sampling rate necessary. What exactly were you planning on doing with this. Maybe there's a better way to transmit..? -Tavys |
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Re: Thelephone line modulation with tv signal
nKode
开云体育oh, btw, they sell things for old tv's that have a
coax to a two wire split forked piece that you screw down... I've got one for an
old console that's not cable ready. They're real common. Considering a telephone
wire only requires a ring and a tip, two wires, circuitry shouldn't be
required....just get the adapters.
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Joshua
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"A meow massages the heart."? nKode / Pulse 8 - aim:jkerseyVCSO ?
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Re: Thelephone line modulation with tv signal
nKode
开云体育what's wrong with using a coax?!
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Joshua
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"A meow massages the heart."? nKode / Pulse 8 - aim:jkerseyVCSO ?
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