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Tuesday, July 23, 2019

An Oscilloscope on your TV

Over the last few days I've been playing around with an old small black and white tv....I did the infamous "Oscilloscope on your TV" thing that's all over youtube and the rest of the web...grew bored with that, so I've decided I want to make it into a fully-functional scope that I can use in my lab. I was pleasantly suprised when I came across the one built in '86, it suits all my needs, it was very generous of them to make the design public domain.

What I was wondering is if any improvements to the design was made. They mentioned the possibility of ramping up the bandwidth to 100 Mhz, and I'm looking at high-speed alternatives to the FETS and drivers and so forth. I am also looking into switching regulators to replace the transformers.

poormans OscilloScope

Do you have any suggestions as far as what the maximum current (and any other important ratings) should be for these replacement devices? Also, a few of the components in the schematics don't have a part number...

1) Resistors and variable capacitors on the rotary switches
2) Transformers
3) FETs and PNP transistors on amp

If you could let me know the values on those components I'd be extremely grateful.

AT USA 2006

I am just leading you to some resources in the web. A Scope can never perform well on TV. It would be better you go for a USB PC Scope that are not only practical but professional too.

Miniature TV converted to oscilloscope - Inside the cabinet of a TV or computer monitor you will find at the back of the picture tube, the yoke coil assembly. Once you locate it, note the clamp that secures it to the picture tube.

The ┬ÁSCOPE - A poormans OscilloScope A (good) oscilloscope was then a very expensive instrument available only to a happy few. As a result many electronics hobbyist made their own scope. The popular electronics magazines in the sixties and seventies were full of scope designs almost always based on vacuum tubes.

Sunday, July 21, 2019

Audio Triggers a Relay Switch

message: Hello there i am just wondering how i would go about trying to get a circuit designed?

The situation i have is i have got a sound signal peak voltage at approx 0.3v. I require this to trigger a switching device such as a relay. There is a 12 volt DC supply available to power up any components.

If you could either send me in the right direction or if possible quote price on having this circuit designed and possibly made it will i will be most grateful.

Thank you CD from UK in 2008

Here are some circuits in the web - Voice operated relay or switch, Clap switch, Sound operated light switch ... all these mean the same. A condenser microphone, pre-amplifier, rectifier, comparator and relay in that sequence. If is the first hobby project for learning home automation and the idea as old as the 70s. It was used in Toys and Lights extensively, when the fad was still on. It is still an excellent learning project that will make an new enthusiast more familiar with components. Avoid using ICs so that your fundamentals become strong.

Using ICs are like ready to cook and serve food packets. Cooking your own meal is similar to ... Using Transistors and discrete components like diodes, zeners, resistors and capacitors. This will strengthen your foundation. Winding your own coils is another thing you have to learn, if you want to be a ace Ham Radio Operator.

Audio Triggers a Relay Switch

Audio Signal Detector Switch - This circuit will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal. It could be used to turn on a relay, routing the signal to were it is needed.

Design of a Clap Activated Switch - This involves the design of various sages consisting of the pickup transducer, low frequency, audio low power and low noise amplifier, timer, bistable and switches. It also consists of special network components to prevent false triggering and ensure desired performance objectives.


Monday, July 08, 2019

Hall Effect Water Meter System

I have 36 water meters below ground level which are exposed to intermittent flooding and located throughout a four acre property. I would like to relocate the meter heads to a central location for ease of reading and protection from flooding. The heads can be removed and are coupled to the base by a magnetic pulse generated by a rotating disk in the base.

A Hall effect sensor would pickup the pulse, amplified as required to drive a coil ( off the shelf choke ? ) that would pulse the meter head at the central location. A conduit runs from the central location to each meter for wires to be run, as few as necessary please. the nearest meter is 60 feet away the farthest is 700 feet away. Please email me for additional info and terms.

Thanks! EH USA  - Email got 2007

This mail was not resolved by me due to a break in communications. I also feel this is a interesting system that can be solved by Wireless Device Networking like WSN - Wireless Sensor networks.

Here is a very old website which has shown home automation interfaces.

Water Meter Monitor - Revisited

Water Meter Monitor - Revisited

"After I received the sensor, some experimentation showed that it would certainly detect the spinning magnetic field of the water meter. See the plot below. It shows actually two 'dips' per revolution of the magnetic drive.

This implies that there are two spinning magnets, each negative dip being a separate magnet. The peak-to-peak amplitude is about 0.1V. Based on the sensitivity of the meter (1V=1.6 Gausss), the amplitude of the magnetic field at the perimeter of the water meter is 0.16 Gauss."

- Edward Cheung