![]() ![]() I've searched various posts and sites regarding conversion of the 0-24v analog signal to the range 0-5v the ADC on the Arduino Uno (actually Freetronics Eleven with ATmega328P) can interpret. The sensor is has only two connections which is used both for power and signalling. I have a proprietary 24v DC analog sensor signal that I'm trying to interface with using a Arduino based microcontroller. The rest are on loan from Google Search under fair use guidelines.Disclaimer: Please be gentle - I'm a newbie with electronics. G) I only "own" the picture of the robot and the schematic. This way you focus on sub-systems that make up the whole system which makes trouble shooting easier. It's all done by smoke and you must do your best keeping it in the wires where it belongs! Fuse your project, and it is always better to go with fast blow fuses, like AG3 glass tubes or automotive fuses.į) As you come up with new ways to do certain portions test them individually instead of as an entire unit. Also, soldering in your receiver is a great idea for routine abuse.Į) Your teacher lied to you about moving electrons being the basis of electricity. It is a best case to use a flyback diode to short the coil to itself to dissipate the power from cooking your transistor.ĭ) I have used an Arduino Uno but have Arduino Pro Mini's I will solder into the perfboard. Also, relays release some power when switched off. You also have to consider the scale of your battery bank versus the generated power. Lead acid batteries can handle some amount of this where LiPO's can't. I have my SSRs protected from the motor freewheeling by bypassing the SSRs and "charging" the batteries. This isn't a huge problem now but will be as you add functionality to the base system.ĭ) Flyback diodes are important in protecting your electronics from the power generated when stored energy is released or your motor is freewheeling. This leads to uneven motor speeds while trying to go straight and would be a great time to use the integrated hall effects sensors. ![]() Mine are around 0.6-0.7V at max throttle. This means finding a set that has similar voltage drop across the output terminals and lower is better for heat buildup. I also was unable to achieve proper tank steering function in my previously mentioned instructable.Ĭ) The SSRs are not a great quality and need to find a "matching" pair to use together. I have done a few test runs and have done fine with no delay and some abuse.ī) I programmed Elevons/Tank steering in my transmitter to make my arduino program simpler. Then each relay would be designated for the modulated voltage signal or ground/return from the motorĪ) Don't be a stick slammer with the transmitter joysticks or you will run into an issue not having a delay when your 12V relays change states. I would want to trigger both at the same time with 24V and would put the coils in series. I kept looking for a suitable relay and came up with the idea of using two 12V single-pole double-throw (SPDT) relays. I quickly found out that these relays are expensive for a 40A load. What if I effectively modulated the input voltage for speed control but switched my motor wires when I wanted to go backwards? This is where I cut out three SSRs per motor and wanted to add a 24V DPDT relay. The third idea came while I was waiting for the SSRs to arrive from China where I saved $4/ea versus ones already in the USA. I then placed an order for 10 SSRs from the wonderful Ebay. You can also feed them a PWM signal to control the speed of the motor. SSRs have internal circuitry/magic that makes it possible to use 5VDC to trigger 24VDC. My second idea, was using solid state relays (SSRs) in an H-bridge configuration. I was kind of lazy and making circuit boards can be expensive. I didn't want to design a circuit board and go through the additional complexity of driving MOSFETS. This is where a charge pump comes in, but that is where I took a detour. I found out that you can't use 5VDC to trigger 24VDC on the high side of the bridge. I first tried building an H-Bridge using N-channel MOSFETS. When you have success you will know where it came from instead of saying "I don't know it just works now!?" This makes it easy to identify your mistakes so you can turn around and have a success that you learned something. Everyone gives me a look when I tell them to set themselves up for failure before success! In short, take notes on what you are doing, changing, or breaking. ![]()
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