Handycam CCD-F370E mini crt

Short story: I have a Sony videocam bough some years ago but I think I never recorded anything with it, it was bought second hand and for some years it worked, I mean, I could see the lens image on the viewfinder but it stopped working some months ago, the camera can't focus anymore and I have only what looks like out of sync in the viewfinder, probably some cap leaked and or out of specs.
Since I never used the camera and there are less bulkier and digital alternatives nowadays, why not open it up and remove some components; being the most interesting parts the microphone, the lens and the view finder. Specially the viewfinder looks interesting to make a tiny oscilloscope (while I don't fix my broken scope) or an ATV video monitor.

Now on to dis assembly:

The viewfinder part...

After searching I found some people in the same path but no detail on pin out for the minicrt, so, on to some reverse engineering.

It took me some 10 minutes to find the connection pinout, just to discover the crt would not give image although the record led (connected to the crt control board) indicated power. I increased the voltage to test on 9V (was using 6V and is correct). Nothing! Bloody hell! I hate reverse engineering!
Stopped and waited some time, then returned and had another look just to discover my fault, I was biasing the power the wrong side, I mean I thought the led was switched by the positive but instead is the negative (cathode, anode is always connected to +), it also helped tracing a big coupling cap connect to the only IC in the board (it had to have power directly connected so easy to trace to power line)..... "et voilá", the thing works but I still didn't connected any signal to the board.

The small component near the crt in the following image is an 1W zener.... it's really small the crt but with the lens it's easy to view.
Now the pinout:
After all this work.... if I had just looked bellow one cap I had noticed that there was an video IC bellow it.... if I looked on the IC datasheet I had easily found the pinout, live and learn! Now I have to trace deflection coils to the AN2512 ("Electronic View-finder driving IC") to make tests on deflection.

Now the lousy video:



Have fun!

The "Speaky" reborn

The Speaky HF SSB/CW transceiver kit was the main reason for this blog to start, at that time I wanted to document the building process of the kit but after a while it became the virtual space for my radio electronics projects.
I did finished the build process of the kit but got some bug's on the first test so decided to stop for a while. Now I will rebuild the kit, mainly the cabling to the main board, I made it short the first time and got to the conclusion I need easy access to make further tests.

Today I started debugging the project, the first problem was the frequency counter, a swapped cable (signal and ground) was the reason for not counting the LO frequency, now it's ok but there are around 30 new cables to be done.... lot's of work for the upcoming times....


Only the 40m band module in place, still need to solder the 17m one and probably add another one, the main board allows for 5 band modules, only ordered 2 at that time.

It was also an opportunity to clean the mess in the bench :)

LASER AM modulator

Here's the LASER pointer AM modulator, QRO version, as promised in last post!



The receiver used in tests is the same I've been using in previous tests except I changed the 2 green LED's for an IR diode.
If the LASER is pointed directly at short distance directly to the diode the receiver (LM386) get's overloaded, just point slight off-side.

I'll stop for now this light comunication tests, was just to test the concept. I also tested the AM modulator circuit against a small crystal oscillator buffer and it worked nice.

Have fun!

Health and a Happy new year

Are all my wishes to this blog readers.... and maybe some Eur/USD/GBP/etc to spend on electronic components :)

Here's the light modulator in QRO version...and a better reception "antenna"!



Will post more details next year! It was made today.

Have fun!

6500K AM transceiver

After the build of the 6500K AM modulator I had to do a compatible receiver. Following the tests with the green LED's I thought they were the right candidates to "antennas"...

before the receiver part build I made a small audio oscillator since it's easier to test with a steady source than a mic, this one oscillates around 1100 Hz.



The oscilator "out" after the pot and 0.22 cap connect's directly to the transmit driver input:

There is nothing simpler, not high performance of course...

Receiving part is just the 2 green LED's connect directly to the input of an LM386 amplifier with 200x gain. Standard from datasheet and no input level pot.

And here the prototype in test:



I got 1 inch range before signal get's to low, in fact signal is just near the noise floor of the LM386, an preamplifier would increase a little bit but using LED's as light receivers isn't the most efficient way of doing things, an LDR or a phototransistor will do a better job for sure. Anyhow it's just a proof of concept....

Have fun!

Powered by led's II

Another test with LED's, last time I didn't tested all in the junk box... now I tested the green variety, 2 in series.



The light emitter in the video is my Christmas self present, one LASER pointer that doubles as a small lantern with 2 bright white LED's. Local electronic store doesn't store LASER led's so for 2.5 Eur I had one, just have to disassemble it for further tests in light transmission. The optics su!"# big time but it works for small scale tests.


I did test also a Ge diode with a glass envelop and it did respond to the LASER light giving 21mV, it was an OA90 type I think.

Trying to scale the led's for power harvesting isn't interesting, it's cheaper to buy a small solar panel (from my head calculation) and also other solutions, will try them one of this days.

Electronics - Zener

I post some schematics, some are mine, mostly aren't.... I do understand some basics on electronics but as year's pass somethings are getting forgotten so here's an exercise to remember....

Zeners are tiny little funny devices.... they sit quiet in their room until someone drops them a voltage over their rated value, basically like diodes but on a bigger scale (voltage wise), and then they tend to conduct some electrons.... I never thought it was so difficult to explain what components do..... let's say a zener is the equivalent of a series connection of diodes but connected the other way around, polarity wise.

So let's see a tipical circuit with a zener:

There's a power supply, Vs a resistor R, a zener (that weird diode) and the famous (or not) NE602.

So let's see from an engineering point of view.... the potencial diferencial sum (basicaly the sum of voltages) in a circuit should be "0" (zero)... if not you are creating an energy monster :) but this doesn't matter for the zener subject...just for puting arrows in the circuit case some old teacher of mine sees this...

On we go...

Let's supose we need to stabilize the voltage in the NE602 at 6.2V (just because it eases some math and circuit simplicity). It's also nice to know that the NE602 needs about 2.5mA (0.0025A) of current to work and we have a power supply of
13.8V (most of the time) and our zener can witstand 41mA (normaly more but this is a tested current value from the datasheet and we whant things cool)

Now, we can do this in two ways....

The worst case scenario and the low power scenario...

* The worst case scenario:

Let's say we can have a problem in the power supply and voltage can raise to 24V

We would have to drop some 17.8V in the resistor to maintain 6.2V in the NE602 so our resistor should be (U/I) 17.8 / (Iz + Ine602) = 17.8 / (41mA + 2.5mA) = 409 Ohm...
Power dissipated in the resistor is: 0.77W
Power dissipated in the zener is: 0.25W

So what about when we are runing the nominal 13.8V:
We would have to drop 7.6V in the resistor (13.8V less the zener 6.2V), if our resistance is 409 Ohm then the current is: U/R = 7.6/409 = 18.5mA that is 2.5mA for the NE602 and 16mA in the zener diode.
Power dissipated in the resistor is: 0.14W
Power dissipated in the zener is: 0.099W

* The low power scenario:
Let's save the planet and make low CO2 emissions:
We have a good 13.8 power supply the NE602 consuption is still 2.5mA and we will give just 5mA for the zener (he must do something and still have some margin for power supply flutuation)
Our resistor is now: U/I = (13.8-6.2) / 7.5mA = 7.6 / 7.5mA = 1013 Ohm
Power dissipated in the resistor is: 0.057W
Power dissipated in the zener is: 0.031W
Much less power than on the worst case scenario...
...let's just see what max voltage the circuit can withstand...
We use the same 41mA max on the zener and 2.5mA on the NE602 so voltage on the resistor is R*I = 1013 * 43.5mA = 44V plus the 6.2 on the zener that's: 50.2V
And what if the voltage drops: let's acount only for the NE602 current so the voltage in the resistor is 1013*2.5mA = 2.53V plus the minimum for the NE602 that we consider is 6.2 then the voltage in the circuit should be no less than: 8.73V.

Conclusion:

The worst case scenario let's you drop more on the power supply voltage (409*2.5mA is less than 1013*2.5mA).
The low power scenario covers you more on over voltage and has less power consumption at normal operating points...you choose!

Have fun!