Mussels...

The problem of being a home brewer/DIY/having the knack ,on electronics is that sooner or latter you end up thinking you can build/make anything...
One of the first things outside electronics I did was changing the car oil, the sparks and air and oil filter.... it went well...but now it's something different, after watching some Australian "Master Chef" episodes I convinced myself that cooking is easy....compared to harmonics/IP3/band filters, etc...

Here's a local recipe with Mussels (they were also "caught" by me).

You will need:

*Mussels
*Garlic
*Onion
*Olive oil

Just pour some olive oil, some chopped peaces of garlic and onion on a pan, take it to the stove in a slow cooking position.
As soon as the onions and garlic start to get a light yellow color (means they are starting to get cooked) pour the mussels inside, keep a low power on the stove, cover the pan and let them cook in the steam. Do not put water or salt, they have plenty of salted water inside. Let them cook until they have the shells fully open.

The mussels should be fresh an alive.

Here's the outcome:

It's more of an entry or "tapas" than a meal.

A circuit in the next post... or another recipe!

Mains filter, results

I told you I would write about the mains filter performance after the little VDR issue (blast off).

Well... did it worked?.....did it?...... n....no! Can't win all the time!

I'm sure the mentioned filter would work in minor interferences from mains, so the filter will be put in line with the transceiver power line (it's 230V AC powered).

I am not the first one to have issues with switching power supplies since by their nature they are an RF source and this one is a beast, 4A at 20V, normal laptops are have half the rate in current, I guess this computer is not very economical in power consumption.

When removing interferences that you suspect are from a power line there is some simple stuff one can do:

*Put a power line filter: Didn't worked in my case. If the power is DC sometimes a simple capacitor in parallel or an inductor in series will do the trick (low pass filter), capacitors "don't like" voltage change so do the inductors with current.

*Invert the power plug terminals: This will work if the source problem is unbalanced (power line wise)

*Some ferrite cores around the power cables. I've used this method wen using the Si570 RF generator close to some testing boards and it works (Now when using the Si570 I power it up from a separate power supply).

*Build a Faraday cage: Will work as long as that any "air" space in the gaps is smaller than the interfering wavelength... but for my case I suspect the interference is getting in from the antenna cable since the FT-102 it's self is build in a metallic "Faraday cage". I discarded the hypotheses of the interference getting picked by the antenna since it's 10m away, never the less further tests will be conducted...like removing the antenna cable and the microphone.
I didn't tested yet was to put the laptop power supply inside the filter cage and earth blindage exiting the power cable or even moving to another plug (it's to far away for connecting the laptop to the screen monitor).

*Put and isolation transformer (230V/230V): That is expensive and I would prefer to put again the small computer previous used that I know causes no interference.

Well...the saga will continue....I will test more this weekend.

6500K AM modulator

...Or a "spread spectrum" AM modulator, 390 to 750nm wavelenght, or 400 to 790 THz..... or a white LED AM modulator... now you get it?

Following some LED experiments I wanted to try some light comunication, so decided to do one of the basic forms of modulated light communications, AM, for good or for worst the idea was just to have some fun....

Here's the transmission part, when time permits (I still have a huge backlog on lower frequencies projects) will make some companion receiver and put a mic on this "transmitter".

As you can understand, first I did the schematic and then the final draw on paper...
Any NPN transistor should work but more led's (more power!) will require a more robust transistor, the speaker was just to ear the modulation noise (touching the LM386 input pin), I had no mic at hand.
The pot set's the bias point, and the led should be always on (a steady carrier!?), changing bright by modulation.
LM386 gain was set by an 10uF cap between pin 1 and 8 as standard design.

You can ear noise and see some modulated light in this lousy video:


Have fun!

Powered by led's

I do like led's but aside the fact they are nice to show power on in circuits I only did some minor tests with them. One of the experiments some time ago was to use a led as a poor and small replacement for a solar cell, yes led's can generate small amounts of energy. Some can sense radiation and other types of PN junction can be nice for temperature sensing (like 1n4148 diode)... normaly components have more than one function you know?! The classic example is a resistor used as a camera flash :) One time action of course!

Next images you have an infrared led, (I think, since I don't remember the specs or even when it was bought) the outer case is light blue and emits no visible light when direct biased.

Here in reverse connection getting some direct sun light.
Two of them in series should give 1.4V althoug on a very small current, this multimeter has 10M of internal impedance but if you put some in parallel you end up with a very small power supply as long as the sun shines...

Here's the "power" from a white color paint!:

Incidently this gave me the idea of using one of this for a very crude Sun photometer.... maybe one of this days...

And in the dark:

This led was the best one I tested, other standard types gave worst results.

Have fun!

Mains filter

A friend gave me one of those new computers....a tablet...:)

...never mind the missing screen (there's an vga plug), it works and it was cheap!

My idea was to put Linux in it and use at the weekend shack, it came with windows something installed and for now will stay that way (sure not for long since I'm a bit allergic to that OS).
After some psk and rtty decoding apps installed, decided to hook it up to the FT-102. I was a rainy day and I was getting a lot of interference, I thought it was the weather but after shutting down the computer I notice the interference had gone and the only (confirmed) source was the computer power supply! Rat's! Something had to be done....

So I came up with the idea of making a mains filter idea. The other option includes a Faraday cage for the power supply or getting another computer.

Here's the assembly of the interference filter for the mains power supply:


well....did it worked?.....no and not tested yet, after powering it up (I should had tested before closing the box) the VDR blew up, I guess that it was underrated or I didn't looked very well to the schematic of the donation computer power supply were I removed it and probably the VDR was not on the mains line and was not rated for over 230V.

Now that I removed the broken VDR I have to wait for the next weekend to conduct further tests.

Here's the schematic used:

..never mind the VDR (it's just for spike protection), it's not installed at the moment. If you duplicate this, get capacitors rated for at least 500Vrms, the ones I used are rated 1KV and came from a computer power supply.
The number of turns it's not critical as long as they don't create a lot of impedance on the mains 50Hz....I guess something bellow 1000 turns it's ok :) The idea is to create some high impedance on HF and VHF.

I also placed a ferrite core (the ones used in computer power cables) around the cables as a "won't hurt, probably will help" option.


The white output is the filtered one (it's an old household mains plug), the other two are input and a not filtered output, they came with the donated box (a broken computer power supply).

There's no reason for this schematic do not work at least reducing the level of interference. If it reduces all ,then it's a bonus.

New 10m radio

I don't have much time to do QSO's, in fact time is short even for soldering.... but I have a new radio.... A "Dragon" delta force.... don't you just love the names some manufacteus give to radios? There's also the same radio under the "Magnum" brand. Probably one of this day's someone is going to build the "Kalash terminator" 10m mobile.... :)
Here's the lousy photo:



10m was hot today, I've heard a lot of QSO's and almost pushed the ptt to answear a CQ call from the USA...maybe tomorow!

My first impression on the rig is a positive one, it works and receives nice, vfo operation is not easy on 1khz step since it counts from 1 to 9 but then returns to 0 without increment the 10's Khz...! It's not build like Yaesu, Kenwood etc, in term's of knobs material and front panel (didn't looked inside yet) but enough for the intended function, a receiver for some dowconverter's I will build.

FM crystal radio

I'm back!...Along with the lousy photos and the rusty English...

Having already build a lot of receivers with different approaches I have never tried FM with a "crystal" radio. Now is the time.

This is a simple circuit and honestly I wasn't expecting much performance but is fun and helps getting some momentum for future builds.

I can only get two very faint stations and with an external amp based on an LM386, my "crystal" earpiece I guess is not crystal....

My implementation



The schematic was "borrow" from here. Go on, see the original and nice implementations on that site.

Original schematic from the author site

L: 5 Turns of 1mm silver wire on an "Edding 3000" pen (around 12mm), diode connects to 2.5 turn (half the coil), spacing is around 2mm
D: OA90 or 1N34 (not sure, it wasn't marked) I tried several glass diodes and results were similar.
R: 150 K
C3: 18p
C1: 82p
C2: used one trimmer of 25p (80pf on the original schematic)
Antenna was around 25cm of wire and the 2 station's received are less than 8 km from the shack.

Have fun.