Automatic Water Pump ON and OFF (2005)

Automatic Water Pump ON and OFF (2005)

This interesting project dated back in 2005 where I was still searching for 2nd job after finish 1 year Internship/On-The-Job training from Atambua City (NTT). The reason I searched for other job was because I believed I deserved something better, because I am always different than other :).

Ok, let’s check what’s so special with this interesting project…
I designed this for my Teacher/Mother house. A small dedication :). This electronic circuit will automatically turn on “electric water pump” after the “lower sensor” is triggered (means the water tank is [almost] empty). After some time the water pump is on and filling up the tank, the “upper sensor” later will be triggered when the water tank is [almost] full. Once “upper sensor” is triggered, the circuit will turn the pump off. It will stay off until the “lower sensor” is triggered again (back to first state in the cycle).

Here we go with the finish view: 

Assembly guide:

• Attach the “auto water pump On and Off” (let’s shorten it as “device”) to nearby water tank.
• Put the water empty sensor (lower sensor – contains of two electrodes) to lowest water level you want it to be detected as empty.
• Put the water full sensor (upper sensor) to the highest water level you want it to be detected as full.
• Attach this device to input voltage 220V and the water pump you want to automate.

Let’s review the schematic I designed:

• This device is powered by 12V DC adaptor as you can see above. It has a 12Vdc relay, 2 NPN universal transistors and sets of electrode. The electrodes I use made of enameled diameter 1mm wire. I stripped the end as a conductive sensor.
• Water pump is ON by default, because of relay NC position (NC means Normally Close). It is not energised by the transistors.
• When the water is filling up the tank and touching upper sensor, there will be resistive connections from +12V electrode to upper sensor and lower sensor by the water (Java water resistance is around 10K Ohms). The water resistance will give current around 11mA to base of both transistors. 

Ib = (12V-0.6V)/10K = 11.4mA
Ib is base current
0.6V is Vbe

• Both transistors is then turned on by the Ib (Ic = hfe*Ib = (hfe around 300)*11.4mA = 3.4A, note that the actual Ic current will depend on actual relay usage and transistor maximum Ic rating which is only around 100mA for BC547). This cause negative pin of Relay is LOW/connected to ground. The relay is energised.
• Energised relay pull its’ switches to NO (Normally Open). Note that left switch bypass upper transistor and let the relay always energised provided lower transistor is still on (=lower sensor is still immersed in water). Energised relay switches the water pump off.
• When the water is used by user, the tank will run empty. Lower sensor will no longer be immersed. Lower transistor doesn’t receive base current, means collector current is also 0. This transistor is off, relay is disconnected from ground; relay is not energised.
• Un-energised relay turn the water pump on… and repeat the first state of this cycle.

Above circuit was designed when I was just graduated from my technology high school. I didn’t understand so much about circuit durability and safety. Now I understand, let us see improvements I drafted in below schematic.

1. Added 1.5K Ohms resistors to electrodes – this avoids shorting +12V power supply to ground by transistor base-emitter (which is only 0.6V) in case the electrodes were accidentally shorted. Otherwise, the adaptor or transistor will be blown off. This case can be happened e.g. when we clean out the tank and accidentally short the electrodes. Independent resistors ensure each base may have different needed bias voltage. 
2. Added diode in parallel with Relay – to swap off spike voltage generated by relay’s inductor when it is “suddenly” turned on. The shunt voltage can damage adaptor and transistors.
3. Replaced stripped enamel electrodes with rust-proof electrodes. I remember the stripped enamel was “electrolised” or oxidised (collecting water’s oxygen). When operating. In long term, it will be rusty. Tin(Sn)/Zn/Ag/Au/Cr/Ni coating on a “built in terminal” will be useful to prevent the rust. Simple and cheap example is AC plug bought from hardware store.

That’s all. Feel free to write a comment or any question. And most importantly, I hope this invention is useful to a lot of people :).

First TV Super Antenna (Gray Hoverman) in Indonesia!

Yes, you are not mistaken in reading above title  :)

I only dare writing this title after try to search 3 times, and found NO POST about making Gray Hoverman Super Antenna from Indonesia! Just there is one blog from Malaysia :)

Here is the snapshot:

What is so special about this antenna? why shall they put a nick name as Super Antenna? it is because this antenna has a very wide band (simply talking: you can pick FM Radio, VHF and UHF using only one antenna!). Then the gain out-competes all of other commercial (& expensive, around US$ 30) high quality antenna in US! For the theory, design and research result, follow this link: http://www.digitalhome.ca/ota/superantenna/. you can build and sell as many as you can since it is licensed under GPLv3 (General Public License)

Design schematic from above site:

important advice from 300ohms (expert user nickname from above web forum):

• reflector to active elements distance 100 mm. do not be farther.
• cut reflector slit around 1 inches (separating gap between left and right reflector) - will result in additional free 0.5 dB gain
• increase distance between active elements to be minimum 89mm to obtain free gain of 0.75dB
• transmission cable 50 feet maximum, because there will be loss around 1dB/50ft

While for my experiment:

• using indoor built-in antenna: captured only 3-4 UHF channels + 0 FM radio.
• AFTER using outdoor Gray Hoverman Antenna without reflector, 6 meters height: captured 1 VHF + 13 UHF channels + 11 FM radios! This includes TV5 (VHF), Mediacorps #, Mediacorps U, Channel News Asia from Singapore and TV3, TV9 from Malaysia. Plus TransTV, NET, MNC, MetroTV, Indosiar... etc from Indonesia! Awesome! The FM radios mostly captured Singapore and Malaysian stations, since Batam stations is not so many.
• update after adding mesh reflector (chicken mesh): received 18 total Channels! Wow!! Additional TV7 (malaysia), Mediacorp asantham (Singapore), etc. but the Singapore VHF TV5 lost its' signal. I am not sure why. It looks like the reflector reduce gain in VHF channels. Sad :( because I like watching english news from TV5.

Here are the photos of my DIY Super Antenna (using cheap PVC tube, joints, and galvanised steel 2.5mm wire):

Here is the build cost: 

• 2.5mm Diameter galvanised steel wire around IDR 6,000 (my case is free). 
• PVC tube: 2 meters x IDR 8,000
• PVC joints: 4 pcs x IDR 3,000
• 15 meters Antenna cable (75 Ohm): IDR 22,000 (cheap cable made in china)
• Black high quality Cable Ties (UV resistant): IDR 11,500
• Super glue (alteco/loctite), plastic hot-melt glue: around IDR 10,000 (mine is actually used/free)
• used Compact Disc, Plastic cap, electric tube (all are for mounting): free
• Total cost:  IDR 39,500 excludes the 15m cable. 

note: based on my research from internet, best and cheapest antenna material is:

1. silver (ups, sorry this is not cheap!)
2. copper
3. aluminum
4. galvanised steel

However all metal above (except silver) will become rusty/corroded which deteriorate the conductivity. Hence you must provide "protective coating". In my antenna, I used my stock of aerosol clear coating (bahasa: philox clear). It's free for me :)

Stands on 6 meters galvanised steel tube:

 

Comparing with my neighbour, 14 TV channels reception are just awesome! Plus I do not need VHF and FM antenna :) 
It became 21 channels after adding reflector, wow...:

Mechanical Traffic Light

This interesting project dated back to around 2002, when I was in my Technology High School of Development, Yogyakarta. Thanks to Pak Edy Rahardjo, who press us the students to be creative. He was very best & inspiring in this way :)

The Mechanical Traffic Light works by contacting "blue pyramidal contact" (or any contact shape will actually work) to each selector switch wheel. Each wheel represent number of road in the junction. It is only 3 roads in above draft. Each contact colour in the wheel represent the lamp to be switched ON. The portion of the switch can be simply calculated as:
Green+Yellow = (360 degree)/n     ;where n is number of roads in the junction
Red = 360 degree - (Green+Yellow).

Rotation per draft above is CW. You can see the "red" light will glow sequentially.
Interesting logic, isn't it?  :D

Ikhtisar

this web page is dedicated to record all of my interesting projects... in case I will need in future :)