Boat battery monitor system5/8/2023 ![]() The difference showed up in a 1V difference in the threshold that the relay toggled, so the ‘virtual’ coil resistance obviously makes a difference. “Yenka” on the other hand has a selection of makes in 5V and 12V coil ratings. In “Crocodile Clips” there is only one relay package available, which is non-specific for the voltage the coil can work with. Running the circuit through two emulators had some interesting results. It would have been nice if I could have used the 'LinkIt ONE' on-board Li-Battery, but this is only available via a manual change-over switch on the board from the USB power source. Secondly, the relay changes over from the main battery which is now compromised, to a back-up battery. Firstly the "DigInPin" gets a clean 3V3 voltage via the zener diode as the way it works is to clamp the voltage to the pin, so you don't need a pull-down resistor as used in a switch circuit HERE There are a number of benefits with introducing the relay in the second circuit. The second pole will serve as a changeover between the two battery supplies, to power the board. ![]() The relay pole shown connected, is to give a "hard" switch-over to the centre zener diode, which as indicated by the volt meter gives a definite change over from 0 to +3 (and a bit) volts, ideal to feed a digital input on the 'LinkIt ONE'. So here I present my master stroke circuit, (drawn in both emulators, to show the differences). This circuit was not going to work without a few more components. So the value kept going down until that nice little animation was back as the LED when up in virtual smoke. Yes the voltage went up as the resistor value came down, but only 0.01V per change. So I started to change the value down the scale of available resistor values. I assumed that the red LED and the 1k resistor formed a potential divider, and a simple reduction in value of the 1k resistor would give me a voltage increase presented to the LED. Fortunately doing a web search I discovered a thread on this forum HERE ![]() This was something I couldn't find on the MediaTek web site, or the forums there. According to my web searches, the minimum input voltage is 2.0V that a TTL device expects. The 'LinkIt ONE' has 3.3V digital inputs I wanted to know if this was enough to trigger one of the inputs. The voltage presented to the red LED is 1.9V. This is the point where I went into uncharted waters. If you get a value wrong, like when I put a 330R in for the right hand 470R resistor, you get a nice animation of the LED going into melt down! The libraries have improved as there are more transistor types to choose from. Did I mention it was quirky?).Īs you change the battery value, the LEDs change brightness. You can insert both meters for volts and current from the same library menu window (Crocodile Clips has only a voltmeter on its button bar, to get an ammeter you have to go into a sub menu. Yenka is an improvement over the previous incarnation. Fine for the home hobbyist but it does mean you can't use it at lunch time! Grab it HERE This is free to download, but due to its "Education" licence you are only allowed to use it "out of school hours". Being less quirky, it is an improvement over the original, so recreating the circuit was straight forward. Created by the same people, it has the same feel to it. The second piece of software I discovered is the successor to "Crocodile Clips" and called "Yenka". The 'Crocodile Clips' library has a transistor that is non-specific, and you can't create or add your own. In fact this circuit according to the emulator will survive 24V, which is a worst case scenario, if someone was to wire the two batteries in series! This type of battery, when it drops to about 11V is due for a recharge, which is a condition I wanted to check for. Reducing the battery volts to 11V turns the green LED off and the red LED on. At the nominal 12V the green LED is on, and the red LED is off. This circuit proved to work well in the emulator. ![]() The one that is going to be fitted is rated at 12V 125Ah, and there are two of them wired in parallel. The source of DC power on a narrow-boat is called a leisure battery. The first circuit I wanted to produce was a simple power indicator. It's quite old now and no longer available, but it did prove to be a good starting point. The first piece of software I tried is called "Crocodile Clips". Well it shouldn't be like that, so I decided to investigate circuit emulators, to get my project off the ground, and ultimately on to the water. I can just about follow what they do, but the success rate of my efforts over the years has not warranted doing an instructable.įollowing someone else's design is fine, when they have already got it working, but try modifying it for something you want, and you enter uncharted waters. Now first off I am not an electronics engineer.
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