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PWM motor speed control, with torque control feedback. Q6 is the mosfet motor driver. Q5 delivers positive voltage to the gate of Q6, to cause Q6 to conduct harder so as to drive the motor speed faster. Q4 and Q5 are the transistors that make up an 'Square Wave Oscillator', The design of...
hobbyist
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750
Now replacing the two 1.8K ohm resistors, for a single pot. of 5K ohms, and using a current limiting resistor at each base of 100 ohms, I now have a manual control signal into the base of these PNP transistors to work the circuit. Built the cuircuit and I get a almost a full range from 0% -...
Designing a PWM unit with manual / electronic speed control. Hi, I have been doing some reading up on how 'pulse width modulation' works, and now I feel like I am ready to design my own version of it using all discrete components. Step 1. Design a 'astable multivibrator circuit' for...
By adding a second (D-flip flop), to couple to the first D-flip flop makes it into a (master-slave) flip flop. I needed to reduce the "NAND" gate pull up resistors from 470K ohms, down to 100K ohms, to keep the outputs more stable, otherwise there was false triggering, due to more components...
Now, next I build a two input "NAND" gate. No design calculations here, just put it together, and through trial and error, pick the right resistor values, that work properly with the rest of the circuit. I found that the 100K base resistors works fine for activating the "NAND" gate, also by...
To make a "data storage circuit" known as a flip flop, it begins with two inverters, coupled back to back, so the output of one feeds the input of the other, and vise versa. This is a tutorial of how to design a very basic digital circuit for storing data known as a flip flop. This tutorial...
hobbyist
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720
Design: Voltage Peak detector 1. Vcc = 12v. 2. Choose VCQ1 output, = 9v. 3. Choose VBQ1 = 8v. 4. VEQ1 = 7.3v. 5. choose RCQ1 = 470 ohms. (to drive a LED output) 6. IRCQ1 = (Vcc - VCQ1) / RCQ1 = ~ 6.38 mA. 7. RE is a split resistance, between the emitter of Q1 and Q2. RE = ( REQ1 + REQ2) =...
Page 3. If this works properly I will post this particular design page in the electronics general category for people to look at and suggest design corrections, for beginners to learn from. This can be scrutinized by people more knowledgeable to give good design suggestions so everyone starting...
PAGE 3 REDESIGN working from input to output stage. At this point I'm running into clipping problems when I add a fourth stage, I check the DC bias for each stage and the VC. is around the 1/2 VCC area. I check the Av. each individually, and I get the gains required, but coupling them is...
Ok Now I've been working on the next stage, and realizing that the Zin is dropping instead of increasing, as I try to get as much gain as possible. Probably if I were to use bypass caps. It would solve most of this but I'm trying to not have to use bypass caps. if I don't have to. My other...
  As a hobbiest (NON engineer), I am designing a small signal amp in the most proper way I know how through my methods of calculations, and imperical breadboarding and measurements and tests, using a calculator breadboard and components, oscilloscope, audio signal generator, resistor sub box...
This is a tutorial on basic transistor circuit design for multiple staging. This is a AC current sensor, based on a "radioshack" 12.6V. 1.2A, power transformer, used as the detector. Prepararation: Begin by taking an ordinary 60W. lamp. Wrap its cord about 4 complete turns longitudenal around...
hobbyist
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555
Primary stall sensor. Under normal forward drive conditions the motor current would flow from positive supply through the series 2-6 ohm resistor causing a small voltage drop to be seen across it than through motor and through its drive circuitry to ground. (I'm so used to analyzing circuits...
hobbyist
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688
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3
This is a schematic of a full adder. Different switch inputs supposed to be 8 pictures. max. is 6 per post. I wish I could delete fig.1. which didn't show up and replace it with the proper picture.
hobbyist
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555
As the emitter resistor (RE) is increased by 10 ohms at a time the dc voltage (VC) changes from a lower output voltage to a higher output voltage. This is due to the fact that as RE gets larger in value less current flows to RC, therefor voltage drop across RC becomes less so VC rises. Now...
hobbyist
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1K
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3
I will try to add basic circuit designs to this blog. It will be like a design diary where I will try to explain my methods of designing transistor circuits. First a little background of my experiance with electronics. I started out in the 1980's with an interest in learning how to program a...

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