As suggested, I bought one of these - ***************************
It doesn't seem to be working, though. When I plug in an audio source, the green LED comes on, but it doesn't seem to be transmitting. Does anyone have a user manual?
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It doesn't seem to be working, though. When I plug in an audio source, the green LED comes on, but it doesn't seem to be transmitting. Does anyone have a user manual?
As far as I can tell, that's not one anyone recommended in the thread to purchase.
Unless I'm mistaken, that's not going to work. All I can see on that board are three crystals, a TX, battery holder, LED and aerial. It looks to be something you hook into another piece of kit, there's no circuitry to achieve transmission of a modulated AM signal at all. I'd expect to see at the very least some, resistors, caps, and transistors or maybe an IC version. Was there a partner modulator module to go with it?
Below is a bare-bones type, £7 cheaper than the one you bought and available in the UK not China. As you can see it has all I described above. J3 is for your jack to input a source (phone, mp3, tape etc). G=GND A=Aerial (short length of wire) for old radio to pick up the modulated signal.
I guess that thing could work, looks from the listing like it can transmit on 1MHz, 3MHz, and 5MHz, which can be selected by those jumpers, not sure how as I also haven’t found any instructions! Do you have access to a radio with a digital frequency readout? Not DAB, I’m talking AM/FM with an LCD display to tell you what frequency it’s on, a car radio would be a good start, although on a UK radio it’ll only let you select 999khz, or 1008khz, try either of those then connect up your transmitter thing and just try changing the jumpers into any possible configuration and see if anything comes through. If you have access to a fancy world band radio, such as one of Sony’s ICF-2001D’s, you could check all 3 frequencies for activity. Worth a go before condemning it as unfit for purpose! If it is useless, then the one Chris mentioned looks a good option.
Why not have a go at building one? You'll learn something along the way, and have fun. Years ago I built this 3D monstrosity, I called it Franken-Mitter. At its heart It uses a TL702, you can increase the range by adding the transistor. As ugly as it looks, it worked. Parts were pennies.
I guess that thing could work, looks from the listing like it can transmit on 1MHz, 3MHz, and 5MHz, which can be selected by those jumpers, not sure how as I also haven’t found any instructions! Do you have access to a radio with a digital frequency readout? Not DAB, I’m talking AM/FM with an LCD display to tell you what frequency it’s on, a car radio would be a good start, although on a UK radio it’ll only let you select 999khz, or 1008khz, try either of those then connect up your transmitter thing and just try changing the jumpers into any possible configuration and see if anything comes through. If you have access to a fancy world band radio, such as one of Sony’s ICF-2001D’s, you could check all 3 frequencies for activity. Worth a go before condemning it as unfit for purpose! If it is useless, then the one Chris mentioned looks a good option.
Regards
Lloyd
Hi Lloyd
Yes, I tried that with a car radio, but picked up nothing. It is sold as an AM transmitter. I know next to nothing about this stuff, but my understanding was that you could plug in an audio source to the headphone socket and then it could transmit on one of three frequencies, via the antenna. It has two sets of jumpers, but I don't know what they are for, I guess one is for selecting one of the three frequencies but I have no clue what the second is for.
I'm stuck with it now so I'd like to get it working, if possible. If not, I'll order that kit that Crusty recommended.
As far as I can tell, that's not one anyone recommended in the thread to purchase.
Unless I'm mistaken, that's not going to work. All I can see on that board are three crystals, a TX, battery holder, LED and aerial. It looks to be something you hook into another piece of kit, there's no circuitry to achieve transmission of a modulated AM signal at all. I'd expect to see at the very least some, resistors, caps, and transistors or maybe an IC version. Was there a partner modulator module to go with it?
Below is a bare-bones type, £7 cheaper than the one you bought and available in the UK not China. As you can see it has all I described above. J3 is for your jack to input a source (phone, mp3, tape etc). G=GND A=Aerial (short length of wire) for old radio to pick up the modulated signal.
It's what you recommend I get. You said to search eBay for "am transmitter", I did and the one I bought is the first search result that comes up 🙂
You said to search eBay for "am transmitter", I did and the one I bought is the first search result that comes up
Indeed, I did, and I also stated it would bring up a number of suitable options. I guess I should have also added, do some appropriate comparisons. My assumption was that you would apply some research to the search findings, not apply the logic to buy the first one on the list!
As a result of misinterpretations, I shall no longer contribute to this thread.
I think that there is a bit of confusion here, the three metal packages are crystal oscillators , not crystal resonators. (Something like this from farnell)
As can be seen from the pcb layout they have power going to them via the modulation transformer.
Only the 1MHz setting (Jumper position 1) is useable with a normal broadcast radio, and should be received around 300m if the dial is is calibrated in wavelength.
I assume that you are using an 18650 battery as recommended.
1. No, I'm not using an 18650 battery, I'm using a DC transformer of the same voltage. Do you think this might be a bad idea? 2. Do you know why there are two sets of jumpers? 3. I tried all 9 combinations of jumpers and scanned the full AM range for each one, on my car radio, I think it goes from around 150 to 1,600 or something along those lines.
Why not have a go at building one? You'll learn something along the way, and have fun. Years ago I built this 3D monstrosity, I called it Franken-Mitter. At its heart It uses a TL702, you can increase the range by adding the transistor. As ugly as it looks, it worked. Parts were pennies.
Awww, construction like that brings back happy memories of my early teenage years with a piece of wood with copper nails banged into it and components/wire soldered to those with my Adcola 😍
I think that there is a bit of confusion here, the three metal packages are crystal oscillators , not crystal resonators. (Something like this from farnell)
As can be seen from the pcb layout they have power going to them via the modulation transformer.
Dear Lord, this thing really is minimalist, isn't it? 😲
I want to freshen up the appearance of the radio, back to looking like its original state. I plan on sanding it down but I don't know what's bet to do next, just use a clear varnish or some sort of wood stain. What do people recommend?
Don't sand it! The veneers are very thin. You will go through to the core white wood.If you really must refinish it, use a dry scraper, carefully, or paint stripper. Varnish looks terrible, like treacle. Clear spray lacquer, or danish oil or french polish.
My advice to freshen up the appearance is to do little more than a gentle clean with a damp cloth and maybe cotton wool buds in hard to reach areas. To sand it will completely spoil it. Varnish the thing and it will look dreadful, like a toffee apple.
The surround looks to be dark painted and minor touching up the chipped/scratched areas with nothing more than a black permanent marker pen will improve it. The wooden front will respond to some scratch cover.
To take it back to completely original state is not realistic unless you are a master cabinet restorer. Most DIY attempts look awful and it shows a mile off.
To understand the black art of electronics is to understand witchcraft. Andrew.
