Softrock40 keskustelussa Tom KM5H on tehnyt FM-lähettimen SI571 piiristä 144.39 MHz alueelle.
Tässä piirissä on analoginen taajuuden hienosäätö. Tom laittoi siihen audiotulon ja näin pienitehoinen lähetin oli valmis. Lähetin kuului ilman vahvistinta saman talon sisällä.
Alla alkuperäinen viesti
I have been sitting on the Si571's for a long time. I finally got up and got something done. I worked with the following part number:
571CHC000219DG with a start up of 144.39. Of course, the frequency can be changed just like the SI570.
Someone suggested putting one 10k from Vc to ground and another 10K from Vc to Vdd and then feeding audio thru a .022 capacitor to Vc.
I started some music on the PC and took audio from the headphone jack to the capacitor. The .022 cap just happened to be handy.
Anyway, I could walk around the house and even in the yard and hear the audio clearly on 144.39.
So it looks like the Si571 could be very useful. I was thinking APRS or a beacon or something like that.
A good start would be Tony's XTALL. This board could be modified for the audio input and then new software. Also, I would guess that Dave WB6DHW might be interested in the minor modification to his board for the audio
Anyway, if there is enough interest, I would be willing to do a group buy on this. There might be a better frequency choice. Also, a different I2C address might be good so we could have a 570 and 571 on the same buss.
I am not sure about the price, but I am sure that it will be more than the 570.
Any discussion and suggestions welcome.
73, Tom KM5H