You know that I normally do not talk about my career, Telecommunications Engineering, in this blog. But I think that this contribution may seem odd to those who you feel attracted to electronics. It is a subject that I had to do with my friend Alberto an AM radio receiver. The result you can see the photo above and in the accompanying video. The antenna is a bit limited, so you can only get a single station. Specifically has been designed to capture some around 1080 kHz (in Grenada Cadena SER, which receives more power.)
I commented a bit about the structure of the apparatus, whose components are welded into a plate of bakelite. On the left is the antenna, which is not only a ferrite cylinder with two coils of copper, which allows an input impedance higher or lower. The resulting circuit is tuned to 1 MHz or so, and is fitted with a variable capacitor.
The next stage is a common-emitter amplifier is also tuned to 1 MHz, which increases the level of the signal captured by the antenna. This is introduced into a mixer that multiplies with a harmonic signal with the same frequency as the station to listen (also fits with a variable capacitor) and, after filtering and removing high frequency components is obtained at last the voice signal demodulated.
The final signal is amplified and passed to the audio stage, that fits so you can hear the speaker. Everything is powered with 5 V, obtained from a 9 V battery from a controller (you can see above the speaker.)
I must say I quite enjoyed doing the radio, although it is true that sometimes a bit desperate and it is indispensable to access to certain equipment (oscilloscope, signal generator and DC source) to go testing each module separately, because, as mountain all at once probably will not work the first time.
I commented a bit about the structure of the apparatus, whose components are welded into a plate of bakelite. On the left is the antenna, which is not only a ferrite cylinder with two coils of copper, which allows an input impedance higher or lower. The resulting circuit is tuned to 1 MHz or so, and is fitted with a variable capacitor.
The next stage is a common-emitter amplifier is also tuned to 1 MHz, which increases the level of the signal captured by the antenna. This is introduced into a mixer that multiplies with a harmonic signal with the same frequency as the station to listen (also fits with a variable capacitor) and, after filtering and removing high frequency components is obtained at last the voice signal demodulated.
The final signal is amplified and passed to the audio stage, that fits so you can hear the speaker. Everything is powered with 5 V, obtained from a 9 V battery from a controller (you can see above the speaker.)
I must say I quite enjoyed doing the radio, although it is true that sometimes a bit desperate and it is indispensable to access to certain equipment (oscilloscope, signal generator and DC source) to go testing each module separately, because, as mountain all at once probably will not work the first time.
0 comments:
Post a Comment