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  • Author Author: shabaz
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ZX2051 AM/FM Radio Receiver Kit Documentation

Introduction

The ZX2051 is a low-cost kit to build an AM/FM radio receiver. I thought it could be fun for kids to assemble. The instructions are in Chinese, so the purpose of this blog post was to document any information needed in English (or other languages) to successfully build it.

Any translations, or advice, is welcome, since I cannot do this entirely on my own : )

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Original Documentation

Since I don't have the copyright to it, I've saved high-res scans of the ZX2051 documentation on a third party server during the time that collaboration is needed, but will remove the link after it is no longer required to act as the only documentation.

There are low-res copies of it here (might not be readable), which I believe is fair use.

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Translation Attempt #1

Google Lens was attempted, with some success and some amusement. It didn't get the translation entirely right I think : )

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Another attempt was only slightly better:

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One more time..

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PCB Layout and Notes

The scan here shows the copper side PCB layout, with some of the important bits highlighted in red.

From what I can tell using Google Lens to do the translation, the quadruple tuning/variable capacitor needs the end with the two wires to be inserted in the red highlighted hole, because one side of it contains the FM capacitors (lower capacitance) but the side with the two wires that insert in one hole, is the AM side (higher capacitance).

Also, T2 is highlighted with a red square. T2 is the metal can with the core that is painted red.

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For the electrolytic capacitors, the hatched/shaded side of the circles in the diagram above is the negative end.

 

To be continued..

More info to follow after this kit has been soldered!

  • in reply to fmilburn

    Hi Frank!

     

    I was very surprised too : ) The 6-year-old was fine with the through-hole, although we didn't get a chance to let him try the surface-mount. The 8-year old (actually he's almost 9 - in one months time) had no issue with the chip, not one solder bridge, which was surprising.

    The soldering station is a JBC model (an obsolete model that I got from ebay) but the handle I got new, it is model T210 (it fits lots of their stations, and some open source ones/clone too). The T210 is a really small handle, it's great for through-hole and SMD. There is a larger handle, T245, that I only rarely use, for things like very large connectors, I think I've got a 3mm tip on it.  The T210 covers 95% of work, and I've never found the need to swap its tip to a different size. It is a 1mm tip, really universal. The cord is really flexible and light.

  • in reply to shabaz

    Hi Shabaz,

     

    Very nice image   and quite impressive. I must do this with my grandchildren.  I would not have guessed a 6 year old would take to it quickly.  Is the iron one of those USB powered ones?   It seems small enough to fit their hands well and the cord flexible. 

     

    Frank

  • Construction was smoother than expected! The kids finished the PCB assembly during their second session, and even got to try it out. They were quite stunned to hear the audio I think. Anyway, final assembly into the enclosure will be next weekend. I'm thinking of making a cut-out and a transparent plastic panel at the back, so they can see the insides.

    Here's a 10-minute video of some of the assembly, and a short demo at the end (AM, and not tuned to a station, it happened to be almost on a station at random, so there's some noise too). We have not done any testing yet beyond that first initial power-up.

     

     

    The kids did all the soldering except the wires of the AM ferrite coil/antenna. That needed the enamel scraped off with a knife too.

    The PCB layout and component references were easy to follow, just a few minor points which I'll document in a follow-up comment later, concerning the orientation of the ceramic filters, and mounting of the ferrite coil/antenna.

     

    Also, one component in the kit was incorrect, it called for a 4.7uF capacitor, but a 47uF capacitor was mistakenly supplied, so we replaced that with a correct value one.

  • in reply to balearicdynamics

    Kids that can solder through-hole, can solder this type of SMD. There may be some preparation needed:

    • With through-hole, you have to teach them a trick to hold the IC from the backside before soldering the first pin.
    • With SMD, you have to teach them a trick to hold the IC in place before soldering the first pin.

    The first one is easier mechanical (the holes help keep the IC in place) but there's more abstraction needed (keeping an object that you don't see - and may get hot right where you put your finger -  locked in place, while fiddling with iron and solder).

    The second one is easier visually (you see all things you are working with but they shift easier) .

    For newbies both are not that easy. Helping them does the magic.

     

    I learned soldering at school at age 13 with big nails, a big solder iron, thick copper wire ... That was difficult enough.

  • in reply to balearicdynamics

    Good question, I wasn't sure, so I looked for a datasheet but I can only find it in Chinese. But I tried the translation on the chip block diagram:

    image

    image

    It looks all analogue though from the circuit, so it may be hard to interface to Arduino, without trying things like tuning diodes, which is difficult on an all-analogue design like this.

    However, there's an NXP chip (also SMD, but large) which works well. I tried it a long time ago, it is TEF6606T. It requires hardly anything, just two hand-wound coils (accuracy was not needed), and a few resistors and capacitors, and it connects to Arduino via I2C. The chip at the bottom of the photo is the audio amplifier from memory. The TEF6606T has AM/FM and tuning all controlled via I2C, and the quality was not bad (car stereo quality, it is a chip designed for in-car use).

    image

  • in reply to shabaz
    it's a large SMD, so I may get the 8-year-old to attempt that, to see what happens!

     

    This was just the point I worried me, and the reason I thought that all was through the hole. But I see, it's nice. As I saw your project I also thought – as you sure know it better than me – if it is there a way to hack it, maybe with an Arduino?

     

    Enrico

  • in reply to balearicdynamics

    Hi Enrico!

     

    Yes, it's a rear-side soldered SMD part, not through-hole part (it's a large SMD, so I may get the 8-year-old to attempt that, to see what happens!).

    It is going to be guesswork for some of the parts, because I can't see how it fits the enclosure yet (there is one hole that could be for a screw, but it doesn't align with anything! so now I'm thinking it is held in place somehow maybe with some speaker clip.. not sure). Also a few through-hole parts may need to be soldered from the other side (and there is no silkscreen on that side) so I'm going to need to watch out for that. The AM/FM switch needs to be soldered from the other side, the only cutout for that is on the back of the enclosure.

  • in reply to balearicdynamics

    It is impossible to edit the previous comment so I add this here. Is the IC SMD so it will be soldered on the opposite side?

  • in reply to shabaz

    Shabaz it sounds a very nice project. Just a question the resistor that crosses the IC does not need to be higher to place the IC under it?

     

    Enrico

  • in reply to shabaz

    Hi Shabaz, it is looking great!  They are going to be really proud of it when they finish. I haven't let my 8 year old grandson solder yet - but it seems it is time to learn.  I will be on the lookout for kits, and may order the radio kit as soon as you pioneers have demonstrated how to build it.