SM2GXN

Hi MNA! No there is nothing wrong with poptronix wireless link my friend :) it's just that it is very high frequency 1250Mhz, firstly there is no PCB (printed circuit board) layout which is very critical at high frequencies, it's a matter of less than mm accuracy, well maybe not that much in this circuit but some RF experience is needed, for the 2nd you have to make an antenna which is not that hard but if you want to go by the book it is. For the third you have to make a receiver for 24cm/1250Mhz and either down convert to the UHF band or demodulate the signal in order to get your audio and video out. That's why I say forget it ;D Hope this satisfy your curiosity MNA

I'm concerned too, as a matter of fact I tried to search for his phone number since we live in the same country but I coudn't find any that matches his name. I don't know if Ante has more info about our friend Staigen.

You are right MNA that circuit is only for video. The link gogo2520 posted show how a RF-Modulator is built, as you see there is input for video and audio. To boost the signal from a RF-Modulator which is usually in the range 60-80dBmV a antenna preamplifier can be used or build an small RF-amplifier that cover a bandwidth of at least 8 Mhz for the UHF channel in use, it has to be broadbanded. The quality you get is same as you get from your video, when it comes to remote do you mean those units you can buy that both transmit video/audio and let you switch channel on another tv-set?

As I told you if range is not an big issue ;D Just connect a short piece of wire to the center pin of the output connector of the RF-modulator and a short piece of wire into the antenna connector of the Tv-set, if the distance between your tv and video player isn't to far you will se the video sent by the video player on the tv screen. You'll have to put your tv on same channel as the RF-Modulator otherwise you wont see anything. Forgot to mention, the two wires act as antennas.

Well. the poptronix circuit... just forget it. You can find an RF-modulator in almost every video player, it's a small box with 4-6 pins, there is inputs for both composite video and audio and a pin for supply voltage. If you look at the rear of a video you'll see it, it's where the antenna connector is.

Hi MNA! These schematics you uploaded are not the easiest to build I would say, to build them you need some "extra" skills in RF technique. Since the range is not an big issue why not use a RF-modulator from a scrap video then you have both audio and video transmitter or build your own: http://www.web-ee.com/Schematics/RF_Modulator/rf_modulator.htm

High sukhbinder! I don't think a tv-set use the mains frequency and its voltage for anything else than the SMPS and the degaussing circuit, Tv-sets have mains rectifier and are primary switched. The horizontal sweep is not the same as the mains frequency but for the vertical it is, the refresh rate is 50/60hz, a tv has a 50/60Hz free running oscillator that is locked when there is a incoming signal (50 or 60Hz) otherwise the picture would roll up or down. Haven't tried myself to drive a mains transformer with square wave but one thing I know is that electrical motors driven by a square wave do make some extra noise :) I think indulis is one among the members that can answer this question.

Thank's indulis! Seems like you are the one to ask when it come to dc/dc converters :D As I see it there is no need to bias Q3 as it will degrade the efficiency, am I right? What's the reason for choosing a logic level MOSFET? Sorry kerem for sort of hiijacking your thread but I hope it's ok as long as we stick to the subject.

Yes you can build a small FM receiver out of an IC as you mentioned and a simple FM modulated transmitter with only a few components, both subjects has been discussed on this forum but I don't remember exact name of the thread,you can also visit the project section and RF circuits where you can find both transmitter and receiver circuits that might fit your needs, I hope you find what you are searching for.

Hi crivoli! Have a look at this link there is some good info on different intercom systems: http://www.epanorama.net/links/intercom.html

Hi crivoli! RF stands for radio requency, FM transmitter is a RF transmitter cause it transmitts RF. A transmitter use RF (usually called carrier) to carry information to the receiver , the carrier can be modulated in many different ways one of them is FM and also the most common used. Carrier without any type of modulation does not contain any information I.e speech or music.

Thank's indulis for excellent explanation of the circuit, I would lika to add a few questions, are R17 just a load and for the second what is R16 doing?

I found the link, it will probably not add any important info on the subject but this is how some of these AC dummy loads are made. Someone on this forum must have made their own power resistors with kanthal, alkrothal or nikrithal wire. Well, here's the link, if you don't understand use http://babelfish.altavista.com/ as translation tool ;) http://www.koowa.com/teikouki/huka/kouryu.html

;D ;D ;D ;D ;D ;D ;D :-[ Me tooo!! Now I know that you can't simply link translated pages by babelfish, how pity! I got the link at work, I'll post it on monday in JP language, I've heard that you speak flawless Japaneese Ante ;D

Thanks Zeppelin! :) Don't know if you got this one? TEK-2430A-UG.pdf

I see :) well I'll do another search in my bookmarks.... I know I've seen user manuals for some of Tektronix scopes but I can't recall where, if I find them I'll let you know

Here is a schematic of a factory made dummy load from 1-32KW to much I guess ;D ofcourse it can be scaled down but the problem is still there on how to make those power resistors to fit your needs ::) http://babelfish.altavista.com/babelfish/tr

Check this link also, not sure if it's still there... http://www.edaboard.com/ftopic135574.html

Hi Zeppelin! I don't know if you meant service or user manuals but here is a link to 2465B service manual and I think 2430A can be downloaded from Tektronix but not sure. http://bama.sbc.edu/tektroni.htm

Audioguru what do you think? As I see it the transmitter has several faults, Q1 wrong way should work as a switch and key the transmitter, Q2 should be a NPN and for the final amplifier why it shouldn't work in class C ::)

Hi rybitski! Check this out: http://demo.apogee.net/foe/ftssph.asp

Hi Zeppelin! This is the way they do it (see attached JPG) but I'm also interested in same question you directed to hotwaterwizard.

Hmmm third post in a row ;D Dummy loads I've built has been for RF and purely resistive, some of them has been air cooled or liquid cooled by oil and I have one which is made of two copper wires in salt/water solution (not for internal use ;D) that give 50ohms. Xenobius here is a link to something that might be of interest, this guy uses heating elements (same idea as Ldanielrosa had) that probably can be used from trashed washing machines for free: http://www.homepower.com/files/shuntregulationhp72.pdf what do you think? I read your last post, I will have to check up on the wire cause I have never tried it myself someone might have more on this.

Ldanielrosa that's an good idea cold resistance of the bulbs results in high inrush current but on the other hand these relays should manage to cope this surge otherwise they will be useless in some applications.

I remeber those big resistor packs they used to load heavy diesel generators when I worked in SAF, they were air cooled but represented only fixed loads not variable. I don't know if it is possible to wind own high power resistors with kanthal, alkrothal or nikrithal, honestly never tried with any of these but whatever dummy load you use you will have a lot of heat transfer. How is that 0-120Kw ac dummy built Ante? Have you checked inside this dummy load, don't say you haven't? ;D