How we helped the blind grandfather. Making the indicator of the level of liquid in the cup with your own hands

Idea and search for solutions

The idea of ​​this post was born spontaneously. Once we had a phone call in our office. I called the 87-year-old grandfather, who through some of his channels found our phone number (he used to work in our organization). Grandpa asked for help. With age, he almost lost his sight and the simplest actions that healthy people do not even think about, have become a problem for him. Even such an elementary thing as pouring boiling water into a cup to make yourself some tea. We imbued with the problem and decided to help.

Naturally, in order not to invent a bicycle, a preliminary analysis of the existing solutions was carried out. Here, for example, an interesting concept of the Singing Circle for the Blind , which was once mentioned on Habré. The idea is excellent, but it seems that it has not been brought to the stage of mass production. Further, on Ebay, acceptable options were found for liquid level indicators in a cup for about $ 20, including delivery. Also on the Russian sites were a couple of options for the price of 400 rubles. As for our location (Ukraine), then everything turned out to be much worse - we did not find any options (yes, maybe we just didn’t search well).

In general, in order not to bother with payment and delivery, as well as to enjoy the very process of creation, it was decided to do the indicator with his own hands. The main goal is to make it as simple as possible, convenient, and, of course, cheap, using what is already at hand. The design was based on one of the existing solutions.
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Electrical circuit

The scheme is simple to disgrace. The field-effect transistor opens when both contacts / terminals are in the water. Accordingly, the sound emitter, which is powered by a 9-volt battery, starts beeping. The power consumption of such a circuit in the operating mode is about 10 mA, and in the standby mode it actually tends to zero.

Equipment

So, we used:
1. The reservoir for shavings from sharpeners for pencils as a body - 5 UAH
2. Two 9 volt batteries of the “Krona” type (one is used as a power supply element, and from the second, no longer suitable for use as intended, only the power connector is taken) - 8 UAH
3. Stainless steel tea handles for contact with liquid - from personal supplies
4. Piezoelectric Sound Emitter (Boozer) KPMB-G2306L - 14 UAH
5. Field effect transistor IRF540 - 4 UAH
6. Two resistors: nominal 500 kΩ and 300 ohms - from personal reserves

Total, the total amount turned out 31 hryvnia (about $ 4), which is significantly less than the cost of all previously found finished products.

Assembly

For a start, we made a soldering iron three holes in the body - two on the side, in order to insert steel pins, and one at the bottom for wires from the buzer. The pins were cut and bent by an experimental method - all sizes were selected by eye. For structural strength, so that the pins do not rotate in the case, a small PCB plate was made with two separate well tinned conductor pads. In order to close the not too beautiful holes, used insulating bushings, which are used to isolate transistors from the radiator.


A double-sided tape was fixed on top with a sound emitter (although it would be safer to glue it). And collected on the wires the whole scheme. All elements were insulated with heat shrink.


Further, all neatly laid in the case and filled with a glue gun.


Here is the finished device.

Results

It remains only to show made indicator of the level of fluid in the case.
This is how it looks on the cup:


And, of course, the video:


The indicator has already been field tested. Grandpa was pleased. He could pour himself boiling water, make tea. The battery was also easily changed by itself.

PS Finally, I would like to add: we often do not understand how things that are elementary for us can be important and difficult for others. Here is a simple device at least a little easier life for a person, and this, in fact, cost us nothing. Before us, no one wanted to help him and this is very sad. Help people if there is such an opportunity, because not all of them can help themselves.