what is the diffirent between 1n4148 and 1n4448? Answered

Hello, i want to know what is the diffirent between 1n4148 and 1n4448 .I  checked the datasheet but i cant find the diffirent .. Thank in advance!

Asked by login721 6 years ago

Do avalanching diodes "latch up"?

While working and revising my flyback driver design, I had one of the 1N4148 diodes that I was using as protection get cooked!  (it seemed to fail short circuit) I have not tested to see if the MOSFET survived yet. Obviously the diode needs to react fast and handle avalanching energy well. Any suggestions? are some beefy schottky diodes suitable? Also, does making any ordinary diode go into that avalanche or zener reverse breakdown region cause it to potentially lock up and conduct for a period longer than the EMF spikes I'm dealing with? Or with any sort of hysteresis (like when using neon lamps)? Originally my wimpy glass 1N4148 diodes was wired in parallel directly across the MOSFET drain and source reverse biased. However, carefully examining this tesla coil schematic,it appears that there is both a forward biased diode in series with the MOSFETs, and another reverse biased diode(s) in parallel across the MOSFET & diode. It does not look like a bad idea given one the reverse biased diodes can shunt EMF spikes that are too large while the other isolates them from the MOSFET. My only concern is how lossy that would be at 12V operation.

Asked by -max- 1 year ago

how do i build a voltage multiplier for changing 6 volts to 12 volts using diodes and capasitors?

Hi, since my last question failed miserable resulting in me wasting a bunch of good dollars on a useless , and at the time what was described as a "voltage multiplier", uln2003an darlington transitor array which doent seem to do anything like i was told, i am going oldschool and building a voltage multiplier so i can switch a 12v relay card from here, to power 2 motors via remote control using a 9 amp 12 volt current (10 bats X 1.2v X 3A )X 3 sets in paralell , for my r/c tank which i have used a receiver from a toy car which i have increased its remote control signal to up to 100m away (its a 40mhz remote from china nothing special). anyway i am trying to aquire a 12 volt current ( any amperage above what seems to be less that 5 ma according to the relay cards description) from my receiver that gives me 6 volts 700ma from the motor and 4 volts 900ma for the servo. recently i lost a diode for one of the 4 relay cards i am using so i sent my mother to buy me a uln2003an from jaycar and a single 1n4148 diode from jaycar as well, somehow she was tricked into buying a 100 bulk pack (wich she payed twice for despite getting only 1 bulk pack) but did get me the diode i needed for the relay to work without blowing the "on " led rendeing the relay for somereason inoperable. i have 99 1n4148 diodes now and i want to know if i can make these into a voltage multiplier for the relay to get turned on at 12 volts, using capasitors as well, i know it can be doen, i just dont know what kind of capastor to use or how to assemble it once i have the capasitor. please help em i have een stuck with this for ages and the answer is no i dont know how to use a transistor to switch the relay all i see is 4 ports 12v in 12 v out (for switching relay on) and the switcing part wich is conected to relay contacts http://www.jaycar.com.au/productView.asp?ID=ZR1105&keywords=1n4148&form=KEYWORD http://www.jaycar.com.au/productView.asp?ID=KC5434&keywords=relay+kit&form=KEYWORD links to the diodes i have and the relay ard also heres the transistor i have http://www.jaycar.com.au/productView.asp?ID=ZK8855&keywords=uln2003&form=KEYWORD despite description it says uln2003an on the chip

Asked by oldmanbeefjerky 7 years ago

Adding custom peripherals to your computer via the serial port

I built a switch for my serial port based on the lirc IR receiver designhttp://www.lirc.org/receivers.htmlI tested it with the program winLIRC. It is designed for recording IR signals, so all it does is measure the numbers of pulses and spaces. When I tap the switch I can see the according pulses and spaces on the screen, so I know it works.I'm wondering how I can add this switch as an extra key. Press when I press it a window minimizes, an icon flashes, it inserts the letter 'k', or just something.Are that programs that I can use to monitor all action on COM1?DCD = pin 1RTS = pin 7GND = pin 5resistor is 4k7diode is 1N4148

Posted by PR22 10 years ago

high capacity joule thief/dc-dc converter

I'm trying to make a dc-dc converter with the following characteristics: Output = 5V regulated at up to 30mA = 150mW Input 1V (or lower) from a slightly flat AAA. Assuming a pessimistic circuit efficiency of 50%, then the input current would need to be 150mW / 0.5 / 1v =  300mA which I think a AAA is capable of supplying. I'm using a variation of "led torch circuit 2" from http://www.talkingelectronics.com/projects/LEDTorchCircuits/LEDTorchCircuits-P1.html, but I've replaced with the 1n4148 with a schottky diode and replaced the 2 LEDs and 29R resistor with a 5k6 and 1k resistor respectively; this should limit the output of the circuit to just under 5v. I have a 150R resistor to provide a 30mA load to the circuit. When the input is 2.4V, the output is 4.62V which is close enough to 5v for me.  But if I decrease the input voltage to 1.14V, then the output voltage falls to 2.7V which is not enough. I have tried half a dozen hand wound transformers with various turns ratios, wire thicknesses and shapes (slug and toroid) but am unable to achieve 5v out (at 30mA) from 1v in. Does anyone have any suggestions as to what to adjust, or perhaps a better circuit?

Posted by GrotBox 5 years ago

Steppers and EMF.? Answered

I have build this Bi-Polar stepper circuit and it works great on the bread board. I etch a board 3 times, 2 with heat transfer and 1 with photo resist. I use 2 completely separate power supplies but with the PCB's i think i am experiencing EMF or feed back. I am using an adjustable schmidt trigger for the clock. What happens is i can hardly get any rpm's, sometimes if the trigger is set just wright it will turn up fairly well, at that time if i try full step the stepper stops turning or will reverse sometimes, if i try ccw it may or may nor reverse and i may stay in what ever direction and any given time . Now at a slow rpm full step normally work's and cw/ccw may or may not work, also it can trigger the half or full step. Also i can disconnect one coil and the stepper will continue to turn, If i try that with the other coil the stepper will stop. So it looks like it is only running on one coil. Is that possible? Keep in mind i have bread boarded it and work's fine. Its just on the 3 pcb's that all this happens. As for the diodes it seams to work better with 1N4001's than 1N4148's I have checked every trace with an DMM and made sure they are going to the correct pins ect. I have tried different IC's L297 and L298 and steppers 2 different kinds and multiples of each. So i am thinking this is EMF, feedback, or a design problem. I have tried to eliminate most every thing i can think of. Comments?     

Asked by WWC 5 years ago