Transistor-Transistor TTL Logic and Totem pole output

Started by Patrick Chung in sci.electronics.basics2 years ago

By combining basic TTL Logic NAND gate with invertors and other gate any logical function can be realized in TTL technology. TTL family of logic...

By combining basic TTL Logic NAND gate with invertors and other gate any logical function can be realized in TTL technology. TTL family of logic circuits is specially empowered with TTL Totem pole output Read more: http://www.cirvirlab.com/index.php/electronic/181-transistor-transistor-ttl-logic.html


TTL input circuit to drive diode

Started by Gary H in sci.electronics.basics11 years ago 5 replies

Hi. I need a little help with something that should be pretty basic. I have a control board that has a TTL output to turn on and off a laser. ...

Hi. I need a little help with something that should be pretty basic. I have a control board that has a TTL output to turn on and off a laser. The laser is nothing more than a diode that consumes about 60mA. So, I want to be able to turn the diode on or off with the TTL output. I don't really know much about TTL requirements. But, would a NPN transistor with resistor between the bas...


MOSFETs and PWM

Started by Randy Day in sci.electronics.basics11 years ago 41 replies

I've built some TTL motor/relay controllers out of NPN transistors in a Darlington configuration, and I'm considering using mosfets instead. ...

I've built some TTL motor/relay controllers out of NPN transistors in a Darlington configuration, and I'm considering using mosfets instead. +V |_ - )| ^ )| relay |_)| | _R_ |/ TTL in -|___|--| |> | GND (cre


pulse counter

Started by George Herold in sci.electronics.basics7 years ago 10 replies
TTL

I want to count TTL pulses from a PMT. (There is already some pulse shaping and discriminator electronics between the PMT and output.) The TTL...

I want to count TTL pulses from a PMT. (There is already some pulse shaping and discriminator electronics between the PMT and output.) The TTL pulses have a fixed width of 300ns and a rate from 10 Hz to several hundred kHz (coming at random times). In the good-old-days all the frequency counters did this just fine. You selected a gate time and the thing just counted the number of transitio...


Cursed

Started by Walt Fles in sci.electronics.basics10 years ago 26 replies
TTL

A princess walked into Radio Shack holding a frog. And she said to the sales person, "can you help me with this, my prince got turned into a...

A princess walked into Radio Shack holding a frog. And she said to the sales person, "can you help me with this, my prince got turned into a frog"? So the salesperson sold her a TTL 7404.


Simple analog to digital conversion??

Started by Anonymous in sci.electronics.basics10 years ago 5 replies
TTL

Hi all, I'm looking for the *simplest* way to convert a 3-state analog input (-5V, 0V, or +5V) into a 2-channel TTL output, as shown in...

Hi all, I'm looking for the *simplest* way to convert a 3-state analog input (-5V, 0V, or +5V) into a 2-channel TTL output, as shown in the following truth table: Input Out 1 Out 2 ------- -------- -------- -5V L H 0V L L +5V H L I'm a noob and have come up with a pretty convolut...


Voltage Regulator to IC

Started by Anonymous in sci.electronics.basics11 years ago 8 replies
TTL

If I am using a voltage regulator to bring a voltage down from 9 to 5 volts should I still put a capacitor before a TTL IC to smooth out...

If I am using a voltage regulator to bring a voltage down from 9 to 5 volts should I still put a capacitor before a TTL IC to smooth out the current?


Looking for old TTL chip...

Started by Impmon in sci.electronics.basics11 years ago 4 replies
TTL

Part number 74256 2-of-8 addressable latch with reset and enable. If there somewhere that still has those in stock at reasonable cost? Or some...

Part number 74256 2-of-8 addressable latch with reset and enable. If there somewhere that still has those in stock at reasonable cost? Or some substitute that would work? -- When you hear the toilet flush, and hear the words "uh oh", it's already too late. - by anonymous Mother in Austin, TX Spam block in place, no emil reply is expected at all.


First post: best place for this?

Started by Ed in sci.electronics.basics10 years ago 5 replies

(Earilier posted in .design - moved here by recommendation.) Many moons ago, I was an electronics repairman in the military. Most tubes had...

(Earilier posted in .design - moved here by recommendation.) Many moons ago, I was an electronics repairman in the military. Most tubes had been replaced by then with solid state, which of course was gaining wide use in the commercial world! I was a dabbler in circuitry, and devoured the TTL Cookbook I bought at Radio shack along with any component I wanted. 25 years later, Radio Shac...


Need Ideas for addressable register IC

Started by Ken Fowler in sci.electronics.basics11 years ago 3 replies
TTL

I need some help. After several years retired and many more years away from cobbling together TTL and field programmable parts, I'm trying to...

I need some help. After several years retired and many more years away from cobbling together TTL and field programmable parts, I'm trying to get my hands dirty again on a project. I am trying to design a replacement UART module for a radio designed about 25 years ago. The original module used a Phillips SCN2661A UART. That one is not manufactured or available anymore. The closest a...


driving a relay with 24vdc low current IO

Started by CptDondo in sci.electronics.basics11 years ago 8 replies
TTL

I have a board with a bunch of TTL-level IO. It can handle a few milliamps (about 10) per IO. I would like to be able to control 120VAC...

I have a board with a bunch of TTL-level IO. It can handle a few milliamps (about 10) per IO. I would like to be able to control 120VAC loads with this board. The relay bank I have needs 50 ma to drive each relay; too much for my little board. Does anyone know of a ready-made inexpensive relay that can switch 10A @ 120 VAC and uses < 10ma to do so? On a related note, does anyone


Unindentify optocouple

Started by mowh...@hotmail.com in sci.electronics.basics11 years ago 2 replies
TTL

I need to replace some optocouple ( round shape plastic casing ). The optocouple which trigger a triac and control by a TTL IC, there...

I need to replace some optocouple ( round shape plastic casing ). The optocouple which trigger a triac and control by a TTL IC, there are printing on the optocouple "MOD 725", i had desolder some good optocouple and measure both side with two output lead, the DMM show infinity in resistance,i could not figure out what kind of optocouple or any substitute on this type of optocouple. Dear memb...


Can someone explain this (simple) schematic

Started by Kasterborus in sci.electronics.basics10 years ago 5 replies

Hi, This is a schematic I've been given for a laser detector circuit. The laser is being pulsed at about 600Hz and the 'PD' (photodiode)...

Hi, This is a schematic I've been given for a laser detector circuit. The laser is being pulsed at about 600Hz and the 'PD' (photodiode) is supposed to detect reflected light from this laser: http://www.flickr.com/photos/20929480@N03/2037052153 The last stage is a comparator - but not well labeled. I think that the inverting input is taking a copy of the TTL 600Hz clock pulse that is ...


Atmel AT89C51ED2 in 40 pin DIP package

Started by Anonymous in sci.electronics.basics10 years ago 4 replies
TTL

I volunteer with a hobby group on weekends teaching kidfs simple TTL concepts as well as a little programming ... to try to encourage them to...

I volunteer with a hobby group on weekends teaching kidfs simple TTL concepts as well as a little programming ... to try to encourage them to enter technology related careers. We need to find some Atmel AT89C51-ED2-3CSIM (or 3CSUM) chips for some projects. Atmel stopped making them and we can't find them anywhere. We really want that part because ... its a 51 family part and we're ...


Multiple Input Pull-down

Started by FyberOptic in sci.electronics.basics9 years ago 4 replies
TTL

I'm having a bit of a quandary. Since I'm still somewhat of a beginner, I hope somebody more experienced can help me out! I have three TTL...

I'm having a bit of a quandary. Since I'm still somewhat of a beginner, I hope somebody more experienced can help me out! I have three TTL logic chips, with one input on each one all connected together to a single input signal. When that main signal wire is connected to ground, the logic chip signals are all low as expected. When I remove the ground connection though, they seem to all go ...


Coil driving

Started by Nuby in sci.electronics.basics10 years ago 15 replies

What's wrong with this picture? TTL control lines with small current sinking capability (say 20ma) need to activate electromagnetic coils...

What's wrong with this picture? TTL control lines with small current sinking capability (say 20ma) need to activate electromagnetic coils (50VDC, 300ma). Each control line gates an SCR which runs Vcc into a coil. The group of coils has a common disable in the form of a big relay that cuts the common connection to ground.


Old 5v TTL: What does a NAND gate looped back on itself do at the analog level?

Started by Thomas G. Marshall in sci.electronics.basics8 years ago 7 replies
TTL

I no longer have access to a scope; I've been wondering about this off and on. Back in college I pondered a NAND gate with one input held...

I no longer have access to a scope; I've been wondering about this off and on. Back in college I pondered a NAND gate with one input held high, and the other input being tied to the output. Basically wondering about the oscilation, and just how "clean" it might be. Now I guessing that it's not going to look anything like a clean square wave, because the transition voltages would be ...


Diodes as transistors

Started by Grant Stockly in sci.electronics.basics11 years ago 9 replies

Is it possible to use two transistors back to back "leg PN leg leg NP leg" to make a transistor? I can't do too much reasearch right...

Is it possible to use two transistors back to back "leg PN leg leg NP leg" to make a transistor? I can't do too much reasearch right now because I'm on a cruise ship and the internet is expensive. I had the idea a few days ago and its killing me. I started with the idea of building a TTL computer. Once I complete that I wanted to design the same computer out of transistors. I'm thinking ...


Diodes as transistors

Started by Grant Stockly in sci.electronics.basics11 years ago

Is it possible to use two transistors back to back "leg PN leg leg NP leg" to make a transistor? I can't do too much reasearch right...

Is it possible to use two transistors back to back "leg PN leg leg NP leg" to make a transistor? I can't do too much reasearch right now because I'm on a cruise ship and the internet is expensive. I had the idea a few days ago and its killing me. I started with the idea of building a TTL computer. Once I complete that I wanted to design the same computer out of transistors. I'm thinking ...


Simple amplifier: simulation & real world do not agree

Started by Jenalee K. in sci.electronics.basics11 years ago 16 replies

I wanted to amplify a TTL-level 1MHz square wave a bit so that it can be used as a clock for a CMOS counter running from 9V. According...

I wanted to amplify a TTL-level 1MHz square wave a bit so that it can be used as a clock for a CMOS counter running from 9V. According to LT-Spice the circuit below works fine, but the real world does not agree (at all). Actually I measured a cut-off frequency of 165kHz and at 1MHz not much is left. Why is the simulation so wrong? 1MHz isn't that high is it? ...