The article explains a simple car tank water sensor alarm circuit using IC 555 and a pulsating signal on the sensing probes to pevent corrosion on the probes. The idea was requested by Mr. Peter.
A "No Water Alarm" Circuit for Cars
I couldn't find how to post a project proposal on your website. May be you can help me with this: I have searched the web extensively for a "No Water Alarm" circuit to use in my car. I want to put a sensor (probes) in the plastic radiator expansion tank that can sound an alarm when it detects no water. I can't find anything on internet, only water present alarms or level indicators. Like rain detectors, flooding detectors etc.
From what I've seen using a 555 timer to create an AC signal to go to the probes is best in order to prevent corrosion due to a DC circuit for the test probes.
probes go inside expansion tank
Thanks for any help you can provide,
Peter
The Circuit Design
Referring to the figure below, the proposed car tank water sensor circuit can be built using an IC 555 astable design.
Although I am not sure whether a pulsating DC or even an AC signal on the water level sensor probes is able to prevent corrosion in it or not, here we employ the principle as expressed in the above request.
In the design the IC 555 is rigged as an astable multivibrator circuit, at a frequency that may be able to produce the most desirable tone on the connected loudspeaker. This can be experimented by adjusting the values of R1/R2/C connected at pin#2/6/7 of the IC.
The pulsating signal required for the probes inside the car water tank is derived by breaking the base connection of the transistor connected with the pin#3 of the IC. In the absence of water, this transistor remains deactivated, which allows the next transistor to conduct and it sounds the alarm indicating an absence of water in the car tank.
However as soon as water presence is detected, the first transistor now begins getting the base bias through probes due to the water bridging across the probes. This enables the pin#3 transistor to conduct and illuminate the LED at its collector, indicating the presence of water inside the tank.
This action also forces the second transistor to stop conducting, and the speaker tone is halted complementing the LED indication regarding the presence of tank water inside tank.
Circuit Schematic
ali says
Hi. Thank you. I’m very interested in electronics, but I am still at the beginner’s level and I need to get acquainted with the design of the circuitry step-by-step so that I can design different circuits myself. please tell us If more details are available about the types of circuits and why it was used for our likes. Also, if you send pdf books or useful resources to my email address.
Many thanks
Swag says
Hi, I appreciate your interest and enthusiasm, however grasping all the minute details can take many years of study and practical experimentation.
Presently I have not prepared an E-book regarding this, although I have been thinking about this since very long. In near future I will surely consider making an E-book for all the interested readers like you.
In the meantime you can consult your doubts and get appropriate answers from me through comments whenever you feel so…
Anonymous says
This circuit will not stop corrosion, corrosion is caused by a net continuous voltage offset – whilst this circuit may pulse the electrodes (has it been tested?) it is still only positive pulses (whose average is a positive voltage resulting in corrosion) – to prevent corrosion the pulses need to be 'net zero' eg pulse from negative to positive symmetrically.
Swagatam says
yes I know that, but corrosion can be caused not just by electrolysis, but due to other factors too…
If possible I will try to change the design although that could make the design more complex….