Anyone Tried One of These...

[ms660]

https://www.silabs.com/Support%20Doc...Si4825-A10.pdf

Lawrence.

[mole42uk]

No, but I fancy having a go!

[Nymrod121]

Very compact device, however the tuning mechanism and scale would be a challenge (as far as I can tell from the lead-out data - and unless I've missed something - there's nothing to indicate the tuned frequency.

[SeanStevens]

Wow, well I have a speaker the size of a 10p coin. Using a 3v lithium coin cell it might be possible to make a radio that fits on the wrist!

SEAN

[richrussell]

I guess you might be able to infer something from the voltage present on TUNE1 and TUNE2.

[ParcGwyn]

I like the look of this chip a lot.

Dave

GW7ONS

Their 'digitaly tuned' version (si4734) is used in some Tecsun radios, it is very good indeed. My Tecsun PL-606 goes with me when walking, great MW and when stationary (i.e. I have found a pub for lunch) it scans the SW so I can listen to available stations. Shortwave, sunshine, a beer and lunch can't be beaten.

There was a development kit for the 4374 (cost about twice that of the radio) is there one for this chip?

[mole42uk]

Originally Posted by merlinmaxwell

There was a development kit for the 4374 (cost about twice that of the radio) is there one for this chip?

Yes there is. I've seen the datasheet but I haven't seen a kit for sale yet.

[RF Burn]

Originally Posted by SeanStevens

Wow, well I have a speaker the size of a 10p coin. Using a 3v lithium coin cell it might be possible to make a radio that fits on the wrist!

You just need a microscopic MF or SW or even VHF antenna to go with that, and a reasonably small battery to supply that 20mA plus an external audio amp for more than a couple of hours...

[Nymrod121]

Originally Posted by richrussell

I guess you might be able to infer something from the voltage present on TUNE1 and TUNE2.

Yes, I'd wondered about that; perhaps a Bourns precision 10-turn potentiometer plus a miniature Beckman Instruments Duodial turns counter (as seen on Tektronix delayed-timebase plug-ins for example).

I did a similar thing on my first FM tuner project back in 1974; frequency referencing involved plotting known stations versus dial number onto graph paper. The only disadvantage was that the scale was very non-linear at the lower end of the band (the 'PW Sandown' was varicap tuned).

The SiLabs website has a lot of support documentation but I've found it oh-so-slow this morning

Best wishes
Guy

[richrussell]

I'd probably stick a microcontroller on it, with TUNE 1 and TUNE 2 connected to ADC pins. Then use a lookup table to produce a frequency value to display on a small LCD or OLED module. If you used an 8 pin Atmel (I've gone off PIC) of some sort, that still leaves a couple of pins free for other control functions.

[mole42uk]

The development module is available from Mouser at £33.03, Mouser part number 634-SI4825-DEMO, unfortunately it isn't a stock item.

[Wendymott]

Ordered 3 from Mouser, see how it goes.

[Wendymott]

Hi peeps...... As I said above... I bought 3 of these "miracle" devices, and I am most impressed and disappointed....... Impressed at the simplicity of the design, not the chip but its applications, i.e no micro controller required, just a few close tolerance resistors and a few 5% resistors and capacitors of easy tolerance.
Disappointed because I think Silicon Industries could have gone that "extra mile".... there is no SSB facility for the shortwave bands, and no AM facility on the VHF range for Airband reception.
I made my own development pcb, using the application note AN738, freely available.

One other "niggle" I found, and I have built two, is the fact that to select the Wide / Narrow function on SW, the radio needs to be turned OFF. If it is on and you shift the switch, it seems to have "latched up". Turn off the power, switch the switch and it will be on the new setting. This is a slight error I think on behalf of Si.....

You can make two versions, the simple one with FM, AM and Shortwave covering 7 - 12.5 Mhz. There is the advanced version with loads of Shortwave band selections. However again a "niggle"..... lots of the SW bands are copies with just the upper or lower ends extended. The application notes are very informative, giving all the required resistor values for various frequency selections. The only requirement is to ensure the entire resistor chain adds up to 500K.
The resistor values were obtained from RS components, however the 67K 1% is not available so order a 20 K and a 47K.
There is another version available the Si4836, which has a Stereo FM facility, it also has other "whistle and bells" allowing storage of Volume levels Treble and Bass controls.

I came across another Si device about 4 years ago, which is the single chip TV tuner, AMAZING..... the complete front end of a TV tuner, however Si were rather angry when I asked for the programming codes, I was not even supposed to have the data sheet...... narky people.
Anyways.... back to the current device.
I attach a few photo's of the second version, and the schematic.

[G6Tanuki]

Must admit, I'm deeply fascinated by this - showing just how much can be compressed into a single lump of silicon these days - even considering the compromises and oddities Wendy mentioned.

I'm assuming it's largely analog: so no access to I+Q components

A while back I borrowed a "Funcube Dongle" - essentially a SDR front-end on a USB stick - and was really most impressed, though the true nature of a SDR is all down to the software you have sitting behind it. A Funcube Dongle, a Pi and an Internet connection, stuck up high and operated remotely, could be just the answer for those who have seriously high local noise-levels.

[Wendymott]

Yes Tanuki.... lots of interesting "stuff" around now....... I bought one of the SDR dongles, but was disappointed , I was hoping for a wider window to view, like a spectrum analyser , not full width, but wider than is available with the software I used... details are a bit vague now, as it was last year, moved on......