TRansmitter

[deleted-331508]

We are trying to do this experiment for the school Science fair.
https://www.sciencebuddies.org/science-f ... #procedure

We got all the products (except batteries and audio cable) from Science buddies .We used regular headphones as the phone cable.We used the radio (530kHz-1700kHz) as the reciever.There is no output.
Should we change the phone cable?
As per the procedure

(Use your wire strippers to cut the 3.5 mm audio cable in half. It has three wires inside: left and right audio (with red and white insulation), and ground (uninsulated).
Strip about 5 mm of insulation off the ends of the left and right audio wires.)

What else could be the problem?
We tried putting only one end of earphone in A5.We get quieting of the background noise at 1MHz on the home radio,but no other output.I am hoping that there is RF at the output,but what should we do to hear the output?
I tried reversing the transformer ,but did not help.I believe we have used 1000 ohms to 8 ohms transformer. Are we not supposed to use step up transformer(8 ohms to 1000 ohms).
Also we used 4 AA rechargeable batteries of 1.2v each.The specification of Crystal Oscillator mention 5V input voltage.Can that be the problem?
We live in Fremont,CA-94538.Can the local AM radio signal be the problem.There is a radio station at 1010 kHz frequency from San Francisco. But I can clearly hear blank when I turn on and noise when I turn off the battery,so I think we are catching the signal.Can you please search for any local signals at 1MHz in my area.
We tried computer ,IPad and Ipod as the sound source.What can we do intensify the input signal?Do you think we should try with the 3.5mm audio cable?
Should I send picture of my circuit .May be that will help.
Please let know.

[norman40]

Hi khadeejabaqui

I’m not very familiar with troubleshooting electrical circuits but I’ll try to help. Perhaps one of the other contributors to the forum will add some comments.

The link you posted did not work. Is this the project you’re working on?

https://www.sciencebuddies.org/science- ... p024.shtml

Your headphone cable should have a common (ground) wire plus wires for the left and right stereo signal. This kind of cable should work if you connect the common wire to A9 and either the left or right audio wire to A5 on the circuit board.

My first suggestion is to recheck all of the connections on your circuit board. Have you tried using fresh, non-rechargeable AA batteries? Also, you might try increasing the playback volume on your sound source.

I hope this helps. Please ask again if you have more questions.

A. Norman