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  2. Welcome to Electronics-Talk.com

    Hello Mike, Thanks for the warm welcome and your quick reply. Richard
  3. Welcome to Electronics-Talk.com

    Hi Richard, Welcome to our community. We are glad you are on-board. Feel free to start a new topic as per your needs. Mike
  4. DIY A Portable Speaker by Yourself

    Wow! Thanks for sharing with us! I will try it maybe within a few days.
  5. Welcome to Electronics-Talk.com

    Hi, My name is Richard Smith, I'm new here in this community! I found this community on the search engine and glad to found this community. Thanks.
  6. Today I want to share a project of making a portable speaker. You all have seen portable speakers becominng popular these days but most of them are quite expensive so I am going to show you how to make you own portable speakers with minimum parts. It will only takes 1 hours to make and test , and it can run on any usual usb charger. SO, lets get started! Step 1: Getting parts and tools Parts required A Amplifier circuit/op amp circuit ( I used a PAM8403 class D 2-channel amplifier circuit, you can buy it here :http://www.kynix.com/Detail/647721/PAM8403.html.) A project casing or a old speaker with space inside to put circuit A aux cable some wires a micro usb adapter ( if you want to use play it using regular charger) regular usb cable Tools required soldering iron soldering wire hot glue stick Step 2: Understanding the circuit The circuit is very simple just hook up two wires to the vcc 5V and ground pin of the amplifier ic connect one speaker to the one channel output name +L -L and other to +R -R, these are the output to our speakers TO connect input to the amplifier,strip off a aux cable from one side and carefully strip 3 signel wires, to check which wire is ground put the multimer on continuit mode and attact one lead to ground pin and other to 3 wires one by one, the wire which will produce a sound is the ground wire Now carefully solder the wire to the ground input point and other to left and right channel inputs( attach any input pin to either left channel or right channel input it doesn't matter) Now our circuit is complete so test it using a 5v dc supply to input and playing music if everything works fine then its time to asse,ble th Step 3: Soldering components together Solder the components according to the described schematic Step 4: Putting circuit in a casing In my case the speaker case itself serve as a casing for my speaker. You can also use a diff casign for your speaker. It all depends on how you use it but the concept remains the same. After soldering the circuit put all the contents carefully into the casing and glue it using glue gun or use my way using a hot glue stick and soldering iron( always remember to clean solder immediately after using hot glue stick) Step 5: Adding power supply You can use tis circuit directly with any standard 5v supply or by using a microusb female adapter(like i did). I salavaged a micro usb female jack from a old powerbank and ued its casing for protective casing of the female jack ( as it is very fragile) to salavage a old powerbank circuit simply remove the battery and put +ve wire on the positive end of the battery connector of powerbank and -ve to the negative end of the battery. I have removed the battery to save some space Step 6: Close the casing now safey close the casing of your speaker and if possible use screw to close your casing as it is easier in the future if their will be any problem Step 7: Testing time Now to test your creation plug the power suplly and attach AUX cable to your phone/ipod etc and see if it works. If you have any QUESTIONS OR SUGGESTION then please feel free to ask in comment section.
  7. I'm trying to pulse-width modulate an output from a 74HC585 shift register. To achieve this, I plugged a PWM output from a teensy 3.1 microcontroler into the output enable input of the 74HC595. The A output of the 74HC595 is then connected to the ground via a 640 Ohm resistor. Voltage between VCC and ground is 3.3V. Then I use the microcontroler to shift 0b00000001 to the 74HC595 and I start to PWM the output enable input at 50% duty cycle. Here is the datesheet of 74hc595 I expect to measure about 1.6V voltage between output A of the 74HC595 and ground. And indeed, if the PWM carrier frequency is slow (100 Hz), that's what I observe. Problem is, when I try to increase the PWM carrier frequency, the voltage between A and ground increase. For example, I measure 2.7V for a 10 KHz frequency. I measured the voltage between the teensy pwm output and ground, and it is as expected : 1.6 V. So, I know ICs can't be fed arbitrary high frequencies, but I was under the impression that 10 KHz doesn't qualify as high frequency. I seem to be unable to understand the problem, so here I am : can anyone explain me the reasons of this behavior ?
  8. I am using LM324N as a comparator which has Reference voltage of 1.2V to +ve terminal. It requires supply voltage VCC=24V & VEE=Gnd.When input is 0V Vout=24 and when input= above reference voltage Vout=24v. Here is the The problem is that lm324n datesheet IC is getting over heated and burning at VCC and Gnd pin.
  9. I seem to be having some problems with hooking up the L7805CV Regulator. When I provide it 12v @2A I seem to be getting an output value of 10.xxV??? What could I be doing incorrectly? Does it matter that the power supply is 2A and the Regulator is 1.5A? Here is the date sheet of l7805cv.
  10. I'm trying to connect a DS18B20 to my Beaglebone Black. Now I wan't to determine the Baudrate but can't find it in the Datasheet of the DS18B20. In the internet I saw different ones (9600, 19200). Can I simply choose one the Sensor pick's up on it? If so up to what maximal rate? Sorry for this RTFM question, but I really can't find the answer for that. Here is the date sheet of DS18B20.
  11. I need to finish a program before I graduate. And I wrote one. However SIMULATOR displayed PWM CLOCK FASTER THAN FOSC When debugging. I can’t found troubles. My code is given below. Hope someoone here can help me ! The datasheet of DSPIC30F2020 #include <p30F2020.h> _FOSCSEL(FRC_PLL); //enable PLL,FRC crystal oscillator _FOSC(CSW_FSCM_OFF&FRC_HI_RANGE); //ban clock to switch,High frequency mode _FPOR(PWRT_128);//power on reset128MS _FWDT(FWDTEN_OFF); //The watchdog timer is prohibited _FGS(CODE_PROT_OFF);//Code protection closed unsigned int const pwmtab[200] = {0,631,1262,1892,2522,3152,3781,4409,5035,5661,6285,6908,7528,8147,8764,9379, 9992,10602,11209,11814,12416,13015,13610,14202,14791,15376,15957,16534,17107,17676,18241,18801, 19356,19907,20453,20993,21529,22059,22584,23103,23617,24124,24626,25122,25611,26094,26571,27041, 27505,27961,28411,28854,29289,29718,30139,30553,30959,31357,31748,32131,32506,32873,33232,33582, 33925,34259,34584,34901,35210,35509,35800,36082,36355,36620,36875,37121,37358,37586,37804,38013, 38213,38403,38584,38755,38917,39069,39212,39345,39468,39581,39685,39779,39863,39937,40001,40056, 40100,40135,40160,40175,40180,40175,40160,40135,40100,40056,40001,39937,39863,39779,39685,39581, 39468,39345,39212,39069,38917,38755,38584,38403,38213,38013,37804,37586,37358,37121,36875,36620, 36355,36082,35800,35509,35210,34901,34584,34259,33925,33582,33232,32873,32506,32131,31748,31357, 30959,30553,30139,29718,29289,28854,28411,27961,27505,27041,26571,26094,25611,25122,24626,24124, 23617,23103,22584,22059,21529,20993,20453,19907,19356,18801,18241,17676,17107,16534,15957,15376, 14791,14202,13610,13015,12416,11814,11209,10602,9992,9379,8764,8147,7528,6908,6285,5661, 5035,4409,3781,3152,2522,1892,1262,631}; unsigned char num; //Look-up table order register unsigned char sign; //Sine table output symbol float sin_l; void PortInit() { // LATE= 0x0000; // E pot reset TRISE = 0x0000; //set E pot to output , 0: out, 1: in TRISB = 0x0000; //set E pot to output, 0: out, 1: in PORTE = 0x0000; PORTB = 0x0000; OSCCONbits.TSEQEN=0;//OSCTUN TUN<3:0> in register adjust FRC oscillator OSCTUNbits.TUN = 0111; /* FRC时钟为15M */ } void PWM_Config() { FCLCON1=0X0003; // Disable the current limit and fault type IOCON1bits.PENH = 1; /* PWM1H PWM module will control PWM output pin */ IOCON1bits.PENL = 1; /* PWM1L PWM module will control PWM output pin */ IOCON1bits.PMOD = 00; /* Complementary output mode */ IOCON1bits.POLH = 0; //Effective if PWMxH pin is high level IOCON1bits.POLL = 0; /Effective if PWMxL pin is high leve /* Load PDTR1 and ALTDTR2 register with preset dead time value */ DTR1 = 64; /* Dead band time Settings */ ALTDTR1 = 64; /* dead time */ /* PHASE1 register */ PHASE1 = 0; /* No phase shift */ /* PWM Time Base Control Register */ PTCONbits.PTEN = 1; // enable PWM module PTCONbits.EIPU = 1; /Register/update immediately effective cycle PWMCON1bits.IUE = 1; //Update immediately effective pdc register PWMCON1bits.MDCS = 0;//PDC provide duty ratio PTPER = 47620; //30mips为47620 ,cycle=(PTPER+1)/120MHZ PDC1 = 0; //Duty ratio reset _PWM1IE=1;//Allow the interrupt request _PWM1IF=0;//Interrupt flag reset _PWM1IP=6; //set interrupt priority level to be 6 _IPL=1;//CPU interrupt priority level is 1 } int main() { num = 0; // A variable initialization sign = 0; PortInit() ; PWM_Config(); while(1);//Have been circulating wait for interrupt } void __attribute__((interrupt, no_auto_psv)) _PWM1Interrupt(void) { _PWM1IF=0;//Interrupt flag bit reset if (!num) /fi num=0,mean that every sign invert the look-up table cycle, used to determine the positive and negative half cycle waveform sign = ~sign; //0 to be 1 ++num; // Sine table order value if (num>=200) //reset num after checking 200 pots num = 0; sin_l= pwmtab[num]; PDC1=(unsigned char)sin_l;//The assignment if(sign) {PORTBbits.RB5=1;}//reversing else {PORTBbits.RB5=0;}// reversing } [/code[ Appreciation!
  12. Hello, Recently I am trying to use TPS7A3001(datasheet) for providing clean and stable +5 and -5 V power for my PCBs. I am aware that the output voltage is adjustable by changing the values of external resistors which is connected between the OUT pin and GND. After reading the datasheet, I have some questions: 1, Basically I know one rule is that the current should be greater than 5 uA. But is there any criteria for selecting proper values of resistors? e.g. I can choose two resistors of 10 K and 20 K or 100 K and 200 K to get the same desired voltage, what is the difference between these two selections? 2, In the datasheet of these two devices, I found: it is recommended that the board be designed with separate ground planes for IN and OUT, with each ground plane connected only at the GND pin of the device. While in the datasheet of the evaluation module TPS7A30-49EVM-567, I found the ground planes of IN and OUT are not separate from each other. I am wondering which rule I should obey when designing my PCBs? And why? Much thanks in advance.
  13. Hello all. Thanks for taking up your time to read my post. I've bought a AC/DC adapter for MAX253CSA which per its specifications should output 5VDC and deliver 3A. I was going to use this adapter to power my BeagleBone Black (BBB) with. However, when I'm measuring the output from the adapter while it's idle (not powering anything) with a good-quality multimeter, it reads 5.24V. The BBB System Reference Manual (Rev. C) states the following: As one can see, my adapter outputs a voltage that's pretty close to the upper limit of 5.25V that the manual says is the maximum supplied voltage for the BBB. Is it still safe to use it to power my BBB with ? Can anyone help me ? I am very puzzled about this question. I do need your help. thanks in advance
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