![]() ![]() INCLUDE Macintosh\ HD:Users:mes:Desktop:motor.cir In MacSpice you can include the subcircuit file, so after adding the appropriate file include card, we replace R M, connected to nodes 1 and 3, with a call to the motor subcircuit ( XMOTOR 1 3 MOTOR). Hopefully I'll have it built and working by part 3. I'll tell you more about the circuit in the next part. So I am going to pull the trigger and order the board soon. Cost for components is about $11 before shipping. I put together a project (collection of components) at Mouser using their cool Project Manager tool. So, I've submitted it to BatchPCB (which I discovered browsing Sparkfun) and looks like it'll cost $7 for the board. Like RCA connectors for injecting signals into audio gear, perhaps? It also has wire pads in case I want to hook up anything else. Since I want to use this thing with an oscilloscope, I thought it'd be really handy to just build in a pair of BNC connectors from the get go. A 9V battery holder will attach to the bottom of the PCB, while the top contains components, including a on/off switch, LED power indicator, waveform symmetry adjustment potentiometer, and. Because that is what's going to power it. The circuit board is the size of a 9V battery. I can't use it for ESR testing but maybe I'll add that capability in the next version. The device will output a 2kHz square and triangle wave signal which is right in the middle of the audio frequency range. With a little trial and error and with help from my oscilloscope I got it set up where I want. So instead of trying to do everything at once, I decided on an ultra simple, one frequency generator. Without going into the gory details, suffice it to say that, in the real world, getting a multiple frequency function generator to work is a bit trickier than LTspice led me to believe. Originally I was going to include a switch to select multiple frequencies. I started with a single supply function generator op amp circuit diagram from Circuit Suggest and then drafted it up in Eagle and then wired it up on a breadboard. My main goals for this project was to try out a short run, cheap PCB fabrication company, play around with Eagle circuit CAD and LTspice simulation, and make a simple, small, but useful function generator. But, having a tiny square wave and triangle wave generator on hand could be useful for audio repair and for demonstrating oscilloscopes I put up for sale. Right off the bat I'll admit this Mini Function Generator electronics project isn't strictly a robotics thing. And, sadly, while I'm no better at it now, at least I stuck my toe back in the water and I can jump in when it comes time to build an oscilloscope calibrator. I haven't actually built anything in an enclosure in 15 years or more. So despite some challenges met with kludges, I'm fairly happy with the results. I swapped out the LM258N Op Amp for an LM1458CN which apparently has a faster slew rate as the trace is substantially cleaner than the one generated by the 258. Note that this isn't my idea, but rather came from this Sparkfun Tutorial. The plastic standoffs are glued to the case with Sure Hold Plastic Surgery. The PCB is mounted with plastic standoffs from Radio Shack. Then I figured why not dress the thing up with a brass insert.Ĭlearance for the switch and the BNC connectors is pretty tight and I had to saw out some unused parts of the PCB to get it to fit. ![]() To cover the mess I made, I used a larger power switch that covers up the original holes. Everything was wrong with this attempt (the picture doesn't even begin to convey how bad it turned out). I cannot cut square, straight, correctly sized holes without better equipment and more patience. My first attempt to install a slide switch on the top failed miserably. I gave up on that one and decided to part it out. ![]() The BNC connectors come from one of the accursed Global Specialties 2002 function generators that I have been trying to get working. It has a removable front panel, a sliding battery door to fit AAs or 9V batteries, and is sizeable enough to fit my various Radio Shack prototype PCBs. I like this box a lot and will probably order several more. It's a tight fit inside that Hammond 1593 project box from All Electronics, but it works. ![]() << My first prototype of the mini function generator is now officially done. ![]()
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