• Electronics and Embedded Programming V3
    1,545 replies, posted
  • building circuits [editline]27th March 2012[/editline] Ultimately what inspired me was my longing to build a nixie tube clock.
  • I'd start by getting an Arduino and some LEDs. Build a simple LED binary clock optionally w/ a precision RTC (Maxim makes a few, I think?). Of course, you'll probably want the usual assortment of resistors, capacitors and diodes. Move onto building a high-voltage supply (boost converter) with a 555. I'm pretty sure you can still buy the old BCD nixie tube driver ICs online. Not sure how much they cost or where to get them, but it's probably easier than building your own driver. Once you've gotten comfortable with your Arduino and RTC, built the HV supply, and acquired the driver ICs and tubes, it shouldn't be too terribly difficult to put it all together. It's going to be a long (maybe expensive?) process though, since you're going to be learning along the way. When you order parts, make sure you get through-hole (DIP or axial/radial) lead packages. TO-92, TO-220, DIP/PDIP are all things to look for. Avoid anything weird like TQFP or BGA, since you won't have the equipment to work with that stuff just yet. Get a breadboard, plenty of wire (~24 AWG), a good iron, fine 60/40 rosin-core solder, copper scrubbies, and a good multimeter.
  • I wanted to ask, I currently own a arduino and some basic parts like resistors capacitators etc. For a new project someone asked me to make them a microphone that can record and then stream that wirelessly to a computer (so that I can then save the sound on the computer) I was thinking of maybe using the arduino + wifi module + a microphone. Unfortunately I have no clue on how to start, any suggestions ?
  • [QUOTE=quincy18;35327240]I wanted to ask, I currently own a arduino and some basic parts like resistors capacitators etc. For a new project someone asked me to make them a microphone that can record and then stream that wirelessly to a computer (so that I can then save the sound on the computer) I was thinking of maybe using the arduino + wifi module + a microphone. Unfortunately I have no clue on how to start, any suggestions ?[/QUOTE] I don't think you'll get any usable audio with an arduino.
  • You could get usable audio, but the problem is that transferring it to the pc is the big challenge. A wifi module costs a fortune. You could try a bluetooth module that has the sound interface.
  • [QUOTE=ddrl46;35327368]I don't think you'll get any usable audio with an arduino.[/QUOTE] I think it just might be doable if you settle for voice-only. Telephones use a sampling rate of 8kHz, which is within the limits of the Arduino's ADC, and it gives you about 16MHz/8kHz = 2000 clock cycles to play around with. If you want 44.1kHz CD quality audio, that would be a little more difficult. You'd need, at the very least, a different ADC.
  • You could run FFT, send that encoded signal to another Arduino, and reverse FFT that encoded signal. But dunno if 2000 clock cycles would be enough to play with. [editline]28th March 2012[/editline] Also successfully did BCM on Arduino (24 leds drived by shift registers). BCM -> better than PWM. Now need to do serial from Windows. But it's fucking retarded or I am retard here. Don't know, will eventually figure it out.
  • [QUOTE=swift and shift;35283046]I have this fm transmitter: [t]http://i.imgur.com/Vo1wN.jpg[/t] so I know I have to make the antenna bigger, but how do I also jack up the power?[/QUOTE] You don't want to make the antenna bigger, if it's tuned to the correct frequency, by FM transmitter I suppose it's 88/108 Mhz? In that case you could go for two copper tubes, each 1,5 meter long, and mount them next to each other with 1 cm space inbetween, and solder a piece of coax to both ends and into the transmitter. Just the standard dipole principe. Considered jacking up power, I don't know if you really would want this. It seems like one of those car-fm-transmitter things. Powering this kind of transmitters without proper filtering will cause alot of spurious emmisions, at for example aviation frequencies. This is because you are jacking up the oscillator power, normally you would have a very weak, but stable signal from the oscillator, and then power it up in a second stage once you get the signal completely clean. To be honest, this transmitter is fun for experimenting in a close range environment, but sooner or later you will need a proper oscillator in order not to get the FCC at your door. I suggest you look up the BF900 oscillator. I think it's a dutch design, said to be very stable and output about 250 mWatts. Great starting point, easy to make. Have made them myself. [editline]30th March 2012[/editline] And remember, a proper antenna is more important than power.
  • How would I use a mini LCD screen with a Netduino? [url]http://www.sparkfun.com/products/255[/url] This LCD has dirvers written in C++ and I plan to use C# for my Netduino projects. I'm new to this.
  • Found a few 6C4 tubes in the storage closet of my physics class and tested em out: [video=youtube;hn1i-HofPCQ]http://www.youtube.com/watch?v=hn1i-HofPCQ[/video]
  • Continued working on my Willem programming station today. Completed layout of the programming interface that will stick out of the front of the unit. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/100_2658.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/100_2656.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/Willem.jpg[/IMG] Three TEXTOOL sockets, two PLCC sockets and over a dozen pins will make up the interface. Need to figure out how to replace the jumper switches though. the three pin ones are easy as they are EITHER/OR and a regular mini-toggle switch will workbut the ones for VPP and PIC type are a lot more complex and have at least two jumpers per setting. I'm wondering if it is worth it to replace an assload of switches with a rotary knob.
  • Audio engineering student here. Built a clone of the Minimoog VCF and I'm currently building a spring reverb unit of my own design. Anyways, looking for an oscilloscope to test some VCO's. Is eBay the best bet or is there anywhere better to pick one up?
  • [QUOTE=Idioms;35362863]Audio engineering student here. Built a clone of the Minimoog VCF and I'm currently building a spring reverb unit of my own design. Anyways, looking for an oscilloscope to test some VCO's. Is eBay the best bet or is there anywhere better to pick one up?[/QUOTE] Assuming you're buying used, yeah. Just make sure the seller can prove it's in working condition.
  • Yeah, eBay's probably your best bet for an o-scope on the cheap. Just gotta make sure it can do what you want it to do. Snagged myself a 30MHz dual-channel Elenco scope a couple of years ago. Didn't have a power cord and I gotta make my own probes ('cause fuck spending $50+ for a piece of wire with a resistor/cap in it), but I have plenty of PSU cords lying around that worked just fine with it.
  • [QUOTE=Zero-Point;35366282]('cause fuck spending $50+ for a piece of wire with a resistor/cap in it)[/QUOTE] [url]http://www.amazon.com/60MHz-Oscilloscope-Clip-Probes-Accessory/dp/B005HEA62G/ref=sr_1_4?ie=UTF8&qid=1333171841&sr=8-4[/url] Or am I missing something?
  • For doing audio stuff you definitely should get a dual-channel scope.
  • Going to the place I got my Philips PM3240 tomorrow, I hope they have some fun stuff this again this year :dance:.
  • [QUOTE=DrLuke;35367380]For doing [b]any[/b] stuff you definitely should get a dual-channel scope.[/QUOTE] 1 channel scopes are practically useless.
  • [QUOTE=ROBO_DONUT;35366708][url]http://www.amazon.com/60MHz-Oscilloscope-Clip-Probes-Accessory/dp/B005HEA62G/ref=sr_1_4?ie=UTF8&qid=1333171841&sr=8-4[/url] Or am I missing something?[/QUOTE] The last time I went probe shopping was in catalogs some time ago where they had all the bells-and-whistles on 'em. Not even 5 minutes after I posted that I found a guy on eBay selling 100MHz probes for $7 a piece. :downs:
  • [QUOTE=Chryseus;35368773]1 channel scopes are practically useless.[/QUOTE] No they're not. I'm always using a 1 channel scope for everything I do, simply because it's only one quarter the size of my dual-channel scope.
  • Alright, so, I have built a radio transmitter using this schematic: [img]http://www.pcs-electronics.com/schematics/Small_Fm.jpg[/img] I went on and created a PCB on SprintLayout, then did the rest of the oxidation processes and such. And it does work, but not on radio frequency. Using an inductance calculator from a program called Rfsim99, I calculated the resonant frequency of the coil to be around 500 MHz - five times higher than standard radio frequency. I then proceeded to do more calculations to see if I can get the resonant frequency to an acceptable value; I came to a conclusion that a 198 nH (30 mm long, 5 mm diameter, 16 turns, air core) would give out a resonant frequency of 103.25 MHz. I changed the coil on the PCB, but to no avail. Here is the layout of the PCB: [img]http://cache.gyazo.com/8cc0581f9be3e926b93312fdcd0d7151.png[/img] Dimensions: 80 mm long, 50 cm wide I addressed some people from various electronics shops around my town, and I got some info. One shop owner said that I must modify C3 until the modulation starts and that with C2 I can modify the emitting frequency - the problem is that I don't know when exactly that happens. So, how can I verify if the modulation started? If you need me to give you guys more info, please ask. Thank you in advance.
  • I'm not sure your calculating the resonant frequency correctly, C2 is in parallel with the inductor so that determines the resonant frequency (1 / 2 * Pi * sqrt ( L * C2)). This results in 113.106MHz with a 198nH inductor and C2 set to 10pF. C3 being in parallel with the transistor determines the amount of FM modulation since the collector-emitter junction acts as a small capacitor controlled by the base voltage, any value between 10-30pF should do the job. Also keep in mind that this circuit is not particularly accurate, the actual output frequency is dependant on a number of factors, the best way to verify it is working is with a radio. Even if you have a scope you can't directly probe the output as that will shift the frequency down although it would verify that it's oscillating.
  • [QUOTE=ddrl46;35368762]Going to the place I got my Philips PM3240 tomorrow, I hope they have some fun stuff this again this year :dance:.[/QUOTE] :o? Where do you go for your fun stuff?
  • [QUOTE=Chryseus;35375863]I'm not sure your calculating the resonant frequency correctly, C2 is in parallel with the inductor so that determines the resonant frequency (1 / 2 * Pi * sqrt ( L * C2)). This results in 113.106MHz with a 198nH inductor and C2 set to 10pF. C3 being in parallel with the transistor determines the amount of FM modulation since the collector-emitter junction acts as a small capacitor controlled by the base voltage, any value between 10-30pF should do the job. Also keep in mind that this circuit is not particularly accurate, the actual output frequency is dependant on a number of factors, the best way to verify it is working is with a radio. Even if you have a scope you can't directly probe the output as that will shift the frequency down although it would verify that it's oscillating.[/QUOTE] I am quite in a pinch with that mathematical formula.. I tried calculating the resonant frequency with it and it gave me 69 MHz.. I think. Can you please calculate the resonant frequency to be between 88 and 108 MHz? Also, I do have an oscilloscope, but it only works up until 20 MHz; my father ordered an easily hackable 100 MHz oscilloscope, so I can tune it up to 200 MHz.
  • [QUOTE=supervoltage;35382691]I am quite in a pinch with that mathematical formula.. I tried calculating the resonant frequency with it and it gave me 69 MHz.. I think. Can you please calculate the resonant frequency to be between 88 and 108 MHz? Also, I do have an oscilloscope, but it only works up until 20 MHz; my father ordered an easily hackable 100 MHz oscilloscope, so I can tune it up to 200 MHz.[/QUOTE] The formula as you should enter it into a calculator is: 1 / (2*Pi*sqrt(LC)) With C2 set to 13.3pF this should roughly set the frequency to 98MHz. To test that it's working put a signal into it, a sine wave for example and get a FM radio out, adjust it across the band until you hear your input signal or alternatively very slowly adjust C2, remember to make any adjustments with a plastic tool not metal, also keep the transmitter away from your body as this will effect the frequency severely. If you still have nothing try increase C3 a little and repeat.
  • [QUOTE=Chryseus;35383416]The formula as you should enter it into a calculator is: 1 / (2*Pi*sqrt(LC)) With C2 set to 13.3pF this should roughly set the frequency to 98MHz. To test that it's working put a signal into it, a sine wave for example and get a FM radio out, adjust it across the band until you hear your input signal or alternatively very slowly adjust C2, remember to make any adjustments with a plastic tool not metal, also keep the transmitter away from your body as this will effect the frequency severely. If you still have nothing try increase C3 a little and repeat.[/QUOTE] Thanks, be right back in a few minutes (or hours) with the result.
  • So that's how they look like? *Tries to look understanding :rolleyes:*