Shahriar

Dear Audioguru Can U give an explanation about what are Compandors and what do they do? I downloaded the NE570 Datasheet but couldn't guess what it does... ThanX in advance Shahriar

Dear coolcat14 There is a project in project section of this site named: "Courtesy Light " it is very similar to what U are looking for, but U should make somechanges... HTH - Shahriar

Dear vigosport I am still working on it and it is going to become an impossible for me to do it. ThanX In advance Shahriar

Thank U very much for all of your Replies.... But dear Kasamiko, about the thing that happens in My PC, I should say that: IT WORKSSSSSSSS!!!!!! truly, Shahriar

Dear Audioguru I found the DC-Converter as same as you said. but the funny thing is that when I try to see the link which I had seen before in MicroCHip product List, it do not show me the schematics. ThanX Shahriar

Dear james120479 Use an Encoder IC In Transmitter and a its OWN decoder in receiver. for example PT2262 as Encoder and PT2272 as decoder. and if U are familiar with Microcontrollers U can send different codes and detect them in receiver by another Microcontroller. For Tx circuit, I should say that it is very difficult to build a very sensitive TX for data sending, The best way is buying a TX Module (i.e. TLP434 as Tx and RLP434 as Rx). If U want to build your Own Tx, build a several FM Tx and connect the input to different pulses with diffrent frequencies. then detect them by a lm565 (PLL IC). Here what U are looking for. but I recommand the first solution HTH Shahriar circuit17.pdf

Hi again Here is the PCB, You should open it with Photoshop Shahriar 30339_11106031-eps.zip

Hi Sorry I write this in this forum, But few days ago I found some good schematics in Silicon Chip website and saved them in my computer, but today when I tried to download some more schematics the website do not show the schematics any more, just showing the Commercial Specifics of the Kits. P.S.For example Look at this DC-Voltage converter. I Built it and works very nice, by changing a resistor I increase the voltage UP TO 40 Volts. ThanX in advance Shahriar Inverter.zip

Hi I want to build a chornometer in an Outdoor place that when someone passes the start line the chornometer begines time measuring. the start Line width is variable between 5-10 meters. Someone told me to do the job with a laser. but the problem is the sensor for the laser. what is the best way to sens a laser with no error. In case of an error the chornometer STARTS. ThanX in advance Shahriar

Dear spleblem The best way is using UM66 IC. It is very small and funny with just Three Leads. it is very similar to an ordinary transistor that you may mistaken it with a transistor. It has three leads, two for Power and On for the Output. each IC has a unique code that represents the melody it has in its memory. U can test it by just connecting 3 Volts to the power leads and connect the output to your PC Line in without any extra hardware. Just do not forget to enable your Sound card Line In. P.S. because the power is 2-3.5V you can run it by watch batteries. (BT66 is the same as UM66) HTH - shariar

By the way there are Lots of these examples in Help folder of protel. Anyway here a one. LampFlashelSignal.zip

Dear Polka I have plenty of Protel schematics and its PCBs. what is the version of your protel? DXP or 99SE? Do you want to simulate it or draw the PCB? Because U can not simulate schematics Involving components which do not have Simulation...( I am not very fimiliar with Protel Simulation. and my protel Version is DXP) Explane more about Your homework...

Dear Maece I know a device that I guess it will help U but I am not sure enough whether it is the thing U are looking for or not If U explane a little about the answering machine U need, Then I think I can help U. Truly Shahriar

Hi I Have a NEC 21" TV (model= MH5) and it goes to Stand-By after 10-12 minutes working in normal condition with perfect Image and it goes to stand-by very quickly in Auto-Searching mode but It doesn't go to Stand-by when the antenna is disconnected. I thought maybe sth. gets hot so I made different parts hot with a Hair-drier(a device which is used to make Hair dry :'( ). when COLD Power supply section and around it (Horizantal section; These two section are close to each other on Chasis) gets a little hot, The TV goes to stand-by faster (i.e. Every 20-30 SECONDS) I changed all tarnsistors and regulator and ICs around it but nothing special happened. Today I changed the tuner and what Happened!!!!!! the TV powers Up and goes to stand-by as soon as I connect the Antenna to the Tuner. The Components which I HAVE NOT changed yet are the diodes and Resistors. Can you guess what Happens? P.S. The schemtic below is related to models with PIP. The Model I am working on does not have PIP Module ThanX in advance Shahriar MH5.pdf

Yes! Using a series of D Flip-Flps. Tricky ;) ThanX - Shahriar

Hi I need an IC (i.e. 74XXX Series) with 8 or more outputs. The outputs will be enabled on by on after each other when I trigger the Clock pulse Input. the important note is that the outputs should stay enabled until I reset the IC. ThanX in advance Shahriar

Hi everyone I know how to use matrix displays an how to multiplex them but I have seen some of these boards in streets in very big sizes. the display animatimations. for example the word "NEC" will move in many directions with too many effects. how do they write the programs. Is there a Simulator for these Boards? What EEPROMS theu use for their Microcontrollers to store such Big size programs. ThanX - Shahriar

Dear smartsarath2003 Put an ameter in series with your load to check how much current U draw from your regulator. putting a 220Ohm load in 24V draws just 110mA and in this case know heat sink is needed. I am sure that you have connect sth. wrong. specialy the pins of lm338 HTH - Shahriar

Dear gnipihz If I were you I would use a mcs-51 microcontroller (i.e. 89c2051). Its programing is vey easy and U do not need any cpmlicated circuit. If U do not know programming U can ask a friend to write it for U but if U are a little bit inteligent U yourself can learn it in just three days. HTH - Shahriar

Hi I want to build a Parallel Hardware lock which can connects between Printer and PC Port. I would appreciate it if I could use a serial EEPROM to Store some data. Any schematic or Idea is appreciated in advance. ThanX - Shahriar

Hi I Need a Long range remote control about 600 or 700 meters. No range Limit is in my area.I have some modules For those garage doors remotes. but their range is not enough, I made a try to make it by using that 4Watt FM Transmitter in project section but the frequency Of the ocillators sometimes changes and because I want to use it for a customer, I am not very sure about it. (Long range Remotes is a main problem for many people) I am curious to know why those garage door frequency never changes? Any schematic or advice for increasing the range of those garage remotes is appreciated in advance. P.S. That 4watt FM Tx in project section works very well and I sent an audio from my PC sound card with very High quality and it has very long range. Shahriar

Dear Knownothing I have built the 4watt Tx and it wotks well. the only Transistor that gets hot is TR3 and needs Heatsink. The other Transistor tempreture is normal and is because of the Frequency they are working. But My Tx Problem is that its frequency sometimes changes when I Disconnect the 12V Power supply and connect it again. HTH - Shahriar

The Last on "TC9409BF" is SINGLE CHIP KARAOKE LSI". I found it in datasheet archive. maybe you can get more information about the others from http://www.datasheetarchive.com/ HTH - Shahriar

Hi I Think this is why a Cap do not pass DC current... The current Formula in a Cap is as Follow: i=C dV/dt + v0 This formula indicates that we have current in a cap If the Cap Voltage Changes (The meaning of dV/dt). So If you just imagine DC voltage across a Cap, dV/dt = 0 ----> i=0 This formula also indicates why we have spark, when we short a charged Cap. when you do this, dt becomes very small so dV/dt increses so current will increase. This Formula aslo indicates why small Caps are uses to remove small and fast changes in regulator voltage (i.e. before and after a 78xx regulator) but how? Delta(v) = 1/C Integral ( i dt ) if dt become very small, Delta (v) becomes zero, it means the voltage across a cap do not accept fast voltage changes. If you ask where did this formula came from, you can find it in Electronic Books. HTH - Shahriar

Here is a PLL FM transmitter. I have not build it yet but I feel it will works nice. http://www.pira.cz/eng/index.htm Click on "FM transmitter 3 W" If it was in Cz Language, go to http://www.pira.cz/ and click English HTH - Shahriar