Owners of small washing machines of the family "Eureka" interested in reliable indication of water level. One such electronic indicator described in article V. Karevskaya "water level Indicator for "Eureka" (in the September issue of "Radio" for 1996). However, for later cars release - Eureka-3M - the recommendations in this article, was unacceptable. Those who bought new cars, we offer to meet with indicator as described in the material published below.
In "Eureka-3M for washing and rinsing has only one (not two, as in "Eureka") the water level corresponding to about one-third of the tank height. Since the drum is filled with linen, blocks almost all visible from the outside space tank, it is possible to visually determine whether achieved or not the water level, it is almost impossible. Moreover, instead of the available water in an older car glass tube Eureka-3M is equipped is more convenient to handle, but at the same time is very unreliable in operation of the float mechanism with pop-up out button. This primitive water-level indicator constantly a little sticky, but with time literally falls apart into its component parts, to extract which from under the bulky reel in the tank is not so easy.
To deliver the owners ' Eureka-3M from the hassles associated with the operation of the washing machine, I suggest to replace it unreliable mechanical unit simple electronic device.
The indicator (see illustration) made three transistors VT1-VT3 and one dichroic led HL1 (ALSA). Washing tank of the machine connected to isolated from network conditional body of display device that performs the functions of a contact sensor B1. Another contact sensor is a metal rod, lowered into the tank at a desired depth and electrically insulated from it.
To the network washing machine is connected using a regular fork to which attached and winding I of the transformer T1. The AC voltage from winding it up II is rectified by a diode bridge and VD2 is smoothed by the capacitor C1. On the VT3 transistor, the Zener diode VD1 and the resistors R6, R7 made simple series regulator. Stabilized DC voltage (about 8 In) connected to upper circuit wire and the casing.
Does the indicator as follows. When the tank car is empty and fork included network, sensor B1 is in the air", and therefore the transistor VT1 (enabled by an emitter follower) is closed. The current flowing through the led HL1.1 (green), very small (of the order of 40 μa) and is suppressed. The transistor VT2 is open, and led HL1.2 (red) lights.
As soon as the machine's tank is filled with water so that the pin sensor B1 will connect (via a conductive current of water) to the body, the VT1 transistor opens and led HL1.1 will light up. The same transistor VT2 is closed and the led HL1.2 will go out. Thus, the ignition green led HL1.1 signals achieving the desired level of water in the tank and the need to stop it filling.
In the washing process due to fluctuations in water level LEDs HL1.1 and HL1.2 alternately glow green, then red. After you start draining used washing solution red led HL1.2 lights up again, and green HL1.1 - dim.
HL1 led is easy to replace two separate LEDs, for example, ALM (HL1.1) and ALCM (HL1.2). Furthermore, it is possible to simplify the device, eliminating red led HL1.2, the transistor VT2 and resistors R3 - R5. But option shown, is preferred, since the same led all the time indicates the machine connected to the network. And according to the guide operation "at the same time to touch the car chassis and to a grounded parts (the pipe, the faucet, the tub) is PROHIBITED." As semi-automatic washing machine Eureka-3M (model NSR-3B) ad hoc network indicator has not, homemade water level indicator in the tank will simultaneously perform the role warning device, warning the user about hazards when the wash.
Transistors CTG (VT1 and VT3) it is permissible to replace CTE and CTC - on CTL. Zener XA (VD1) it will replace XA, XA or XA. Instead of the diode bridge KDA (VD2) can be used KDB or CDV either to collect the usual bridge on four separate diodes, for example, CDA, KD102B KDA or CDB. All resistors - MLT-0,125, ALT-0.125 or sun-0,125. The capacitor C1 is any oxide, with a rated voltage not less than 15 V. The transformer T1 is applied ready - filament from the old tube TV. In the idle on the secondary side must be a variable voltage about 7.5 V.
All items (except the sensor, transformer and LEDs) mounted on plastic Board dimensions 60 x 60 mm Mounting - printed or mounted. The led is glued with glue "Moment" to the top of the plastic base. Do so: in front of the signboard and the panel above the inscription "Eureka-3M neatly drill through the hole first with a drill diameter of 3 mm (roughly), and after this is 5 mm in diameter (completely). In the resulting hole from the inner side machine insert the led and stick it.
Before proceeding to the installation of the contact sensor B1, you want to retrieve from cars still float level indicator.
This white button old water-level indicator tweezers to lift the level of "red lines" and fix in this position, pressing the button to her guide. Then grab the button with pliers and pull it out together wearing the button red plastic tube - the actual color indicator. The remaining parts - restrictive metal washer, wire rod-pusher himself a plastic float will fall to the bottom of the tank.
To extract them from there, and along with all accidentally fell into a tank of extraneous items, machine gently flip side, previously tucked under her some old thick magazines to take her side wall. Then turns the car wheels up and lifted her, set on two stools with upholstered seats, the oversight side other. Wherein the handle switch operations should hang straight without touching of stools! Then Unscrew the six (out of eight) screws M6 mounting side the walls of the machine, three of them off. The fourth wall (which is omitted the power cord) remains in place. Next, Unscrew the six screws M8 with nuts, securing the tank to the two metal parts on top of the plastic base machine.
Then, holding the massive iron load-damper, on the one hand, and a large belt pulley on the other tank, with the bottom of the machine, it bed, work electric motor and other parts, carefully lift above the base, and the resulting backlash from both sides of the stack all the same magazines. Now it is easy to clean the cavity of the tank from the outside.
Before the separation of the tank from the base on its side with a soft pencil cause the projection of the axis of the button float level indicator, rather it a cylindrical guide. This line will allow you to drill a hole with a diameter of 3 mm at a distance of 4...5 mm from the top (now bottom) of the tank. After that the thin strap in stainless steel tank removed with a round file, giving the cut-out shape of the Latin letter "U". It is through this cut will be the wire from the sensor B1.
Next, the tank is again fixed to the base and turn the car in normal position. In the former cylindrical guide button red-hot spicy the highlight without a hat (with a diameter of about 2 mm and a length of about 20 mm) caution burn through hole (it is important not to damage the outer "shell" of the base!) so that through it you can skip the wire from pin sensor B1. Wire should pass from the upper hole with a diameter of 21 mm (from the guide button) on a plastic base in the internal cavity of the machine. The axis of this hole located at a distance of approximately 5 mm from the upper edge of the cylindrical the guide and passes in the direction from the center to the periphery.
But the wire from the sensor B1 will not go out of the machine, so once it is omitted from the guide through the plastic base and previously made "U"-shaped cutout in the tank, it should rotate in the direction of the reed switch, triggered by the permanent magnet disposed in the plastic lid of the machine. The wire is placed close to the wires from it switch, and is supplied to the free arm (only goes through it the network cable) on which you place not only charge with the details, but the transformer T1. To connect the sensor B1 used solid copper wire in PVC insulation (telephone cable). Its internal the diameter is 1 mm, and the outer (with insulation) is approximately 1.5 mm.
Pin sensor B1 is made of a stainless steel rod (08KH18N10T) with a diameter of 3 mm and a length of 300 mm. the Sensor operates at a constant current, but it is very small (about 40 μa), therefore, electrochemical corrosion can not be taken into attention. The rod is passed through the hole in the rubber stopper, with tightness inserted in a cylindrical hole with a diameter of 21 mm rail. Top the bar end (after it is soldered a ring of copper wire) cover rubber cap, the outer diameter of which (before Assembly) was equal to 22 mm. thereafter the upper end of the rod tin with "soldering acid" (chloride of zinc). At the bar wearing a PVC pipe, and so, to the lower end remained insulated from the water to a height of about 10 mm. In the stopper rod is held in place by a tight fit. To the lower end of the sensor not accidentally touch the side wall of the tank, wearing tight rubber washer thickness of 5 mm and a diameter of 10 mm.
Author: V. Bannikov, Moscow