Good IC's to mess around with (and a question about flip flops) - Page 1
Forum section: electronics / beginners

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 25, 2016, 02:36:40 am
content: What are some good IC's to mess around with on a breadboard (other than the 555)?Another thing, how does a flip flop work? I understand logic gates, but flip flops are really a mystery to me.

author: Cliff Matthews
author_rank: Unknown
timestamp: October 25, 2016, 03:03:39 am
content: Hello fellow Canadian! I don't know if you're in the belly of the beast (Ontario) but getting neat IC's from ebay can be subject to tax if you order more than 20 bucks worth. Have you taken a look locally at DIPmicro.com in Niagara Falls? They ship usually in less than 36 hours and If you're into LED's, they've got lots. I'd nominate trying out a couple of chained LM3914's ($0.84) to make a voltmeter.http://www.dipmicro.com/store/index.php?act=viewCat&catId=634Also, Google Dipmicro coupon codes (currently "WINTER2016" or "BERRYPIE") to get a discount or free shipping.

author: rstofer
author_rank: Super Contributor
timestamp: October 25, 2016, 03:06:56 am
content: Op amps are fun and a great building block. If you are interested in digital, you might as well skip over discrete logic (7400 series or equal) Nobody is using chips for logic since the advent of the CPLD or FPGA. For microcontroller projected, the Arduino is a great place to start.The most important flop today is the D-type. Here is a discussion and animation:http://www.falstad.com/circuit/e-edgedff.htmlThe reason the D-flop is important is that these are what you will find inside CPLDs or FPGAs. In the old days we used to use a lot of J-K flops but I haven't seen them in years. They're still made but I haven't seen them in a project.

author: Cliff Matthews
author_rank: Unknown
timestamp: October 25, 2016, 03:08:13 am
content: Sorry! I got off on a tangent there and forgot the flip-flop..http://www.talkingelectronics.com/projects/5-Projects/Projects16.htmlIn general, I find talkingelectronics is a very resourceful site for neat ideas. BTW, welcome to the forum!

author: Cliff Matthews
author_rank: Unknown
timestamp: October 25, 2016, 03:35:48 am
content: Quote from: rstofer on October 25, 2016, 03:06:56 amThanks! I saw that site some time ago, but forgot to bookmark it. For our OP, this link pulls up a JavaScript circuit simulator:http://www.falstad.com/circuit/circuitjs.htmlPull down the last menu "circuits" and spend an evening (or two) fooling around with all the circuit examples.. very cool!

author: Legionary
author_rank: Contributor
timestamp: October 25, 2016, 05:19:07 am
content: LM741's are my recommended breadboard op amp for analog prototyping. Fairly mundane, but its performance is good enough for anything you would build on a breadboard most of the time.For digital stuff... I don't really use discrete logic chips anymore instead I use ATTiny85's and ATTiny84's and write some simple code to serve for any sort of glue logic.They come in DIP packages, are cheap, and are completely self-contained, just add Vcc. An AVRISP mkII to program them would only set you back maybe $30, or you could get the Dragon for $50.I would suggest building a small wiring harness with jumpers for the programmer so it is easy to connect to your circuit.I would venture saying a few discrete buffers would come in handy too for driving current, but you would usually be better off just building a proper output stage to handle whatever current you need; would learn more too.

author: Brumby
author_rank: Unknown
timestamp: October 25, 2016, 06:53:13 am
content: Quote from: Cliff Matthews on October 25, 2016, 03:08:13 amAn important detail (I think).... there arethree formsof this circuitThe above is an example of an astable multivibrator - but there is also a monostable and a bistable version. The bistable is what I would call a flip-flop.The difference between the three is only with two components.The astable version has two capacitors (as shown in the above diagram). The transistors take turns charging and discharging the capacitors. It has no stable state and will start off on its own because of subtle differences in the components.The monostable version replaces one of the capacitors with a resistor. With this, the circuit will settle in one particular state. It then requires a 'trigger' on one of the transistors to start the charging cycle of the remaining capacitor. Once this cycle is complete, the other transistor will turn back on, returning it to the original state - and the circuit will stay in this state until another 'trigger' pulse.The bistable version has both capacitors replaced with resistors. It has two stable states. Once one transistor is turned on, the other is off. The state can be changed by a trigger to the appropriate transistor - and the state will stay that way until the opposite trigger is applied.A bistable multivibrator can, therefore, 'remember' a particular state while ever there is power applied to the circuit.There is a variation of the bistable is where an incoming trigger pulse can be steered to change the state. One pulse will change it over and the next will change it back. This is a simple divide by two function.You can go from there.........

author: tautech
author_rank: Super Contributor
timestamp: October 25, 2016, 07:17:49 am
content: There's a few I often knock something simple together with:ICL76654093400140464047, 453840134069And one that I found perfectly suited for a toggling action I needed, a 4077 XNOR gateAnd this simulator can be handy to help visualise functions:http://tams-www.informatik.uni-hamburg.de/applets/hades/webdemos/00-intro/00-welcome/chapter.html

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 25, 2016, 08:09:31 am
content: LM3914, by the way, is a unary 10 bit ADC. It can be used for many interesting things where a sequence or selection of bits is required.Tim

author: Cliff Matthews
author_rank: Unknown
timestamp: October 25, 2016, 11:27:05 am
content: Quote from: T3sl4co1l on October 25, 2016, 08:09:31 amI've got 6 older 80VA Hammond 10v-CT transformers to series chain for a 0-to-75v 5amp linear power supply. A goal in my learning will have the LM3914 auto selecting taps in tandem with a bunch of MOSFET's and 6amp bridges pulled from PC PSU's.(Dave might say something like, "this is old school, none of this PIC/AVR rubbish..")

author: Kalvin
author_rank: Super Contributor
timestamp: October 25, 2016, 12:07:56 pm
content: Quote from: Legionary on October 25, 2016, 05:19:07 amFor Arduino projects and a like using only 3V - 5V power supply, the 741 will not work any more. Luckily there are op amps that are suitable for the low voltage application that are still available in DIP8 packages. If one wants to use an op amp that is not available in DIP8 package, one can but cheap adapter PCB which will convert a SMD device to DIP8. These adater boards can be found from eBay using keywords: SMD adapter boardTI has TLV2372 series:http://www.ti.com/product/TLV2372up to 16V. Also the LMV358http://www.ti.com/product/LMV358(up to 5.5V) may be useful, although its common mode input range is from the negative power supply up to (positive power supply - 1V).Microchip has also some op amps that are useful for the low voltage applications up to 5.5V:http://www.microchip.com/wwwproducts/en/MCP6021andhttp://www.microchip.com/wwwproducts/en/MCP6V26for example. These are a bit more expensive, like $1 - $1.5 / ea. when bought from Microchip directly.Maybe other users are able to give more suggestions for cheap and general purpose op amps usable for the low voltage (5V and less) circuits.

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 25, 2016, 08:25:53 pm
content: Quote from: Cliff Matthews on October 25, 2016, 03:03:39 amThanks for that link. Although it isnt as cheap as the chinese sellers on ebay and doesnt have as much selection, it still beats waiting 6 weeks for something to ship from china.

author: dentaku
author_rank: Frequent Contributor
timestamp: October 25, 2016, 10:21:04 pm
content: The 74HC595 Shift Register is always useful to learn about.Go tohttp://www.doctronics.co.uk/resources.htmland see if any of the examples seem interesting to you.I like the 40106 for making simple oscillators and clocks for other old type logic chips.The 4040B, 4020B counters are fun to mess with and so is the 4017B. Decade/up-down counters are fun for beginners because you can make great looking blinky things.Most of these chips aren't used in modern products but I can see how it's fun to learn about.Salvage some LM358 opamps from dead electronics. They might not be great opamps but they come in handy for experimenting.You might also want some Darlington array chips like the ULN2003 and ULN2803.

author: Kalvin
author_rank: Super Contributor
timestamp: October 26, 2016, 12:29:21 pm
content: 74HC86 and CD4070 Quad two-input XOR-gate are very flexible devices as they can be used also as programmable inverter: Run the signal through the gate and tie the other input to ground, the signal will pass through unaffected. Tie the other input to VCC and the signal will be inverted.

author: KerryW
author_rank: Regular Contributor
timestamp: October 26, 2016, 02:54:41 pm
content: XOR gates can also be used to convert Grey code to binary or binary to Grey code, or to make an adder, or to convert step&direction to H bridge.V-F/F-V converters.XR-2206. Get them while you can, I heard they will stop making them. Been hearing that for 30 years.Go to Futurelec.com and look through their ICs, especially the Special Function ones.

author: ebclr
author_rank: Super Contributor
timestamp: October 26, 2016, 03:10:21 pm
content: 2 IC's that you can do a lot of stuffMAX® II CPLDhttps://www.amazon.com/gp/product/B00EYXM56G/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1Cypress PSOChttps://www.amazon.com/Development-Boards-Kits-Prototyping-piece/dp/B011NB3FPG/ref=sr_1_3?ie=UTF8&qid=1477494560&sr=8-3&keywords=cypress+psocWith those 2 you can play on analog and digital world, will cover 95% of existing single function chip

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 26, 2016, 09:00:38 pm
content: Another thing, are the ic's on aliexpress and ebay legit? Or are they fake?

author: Bryan
author_rank: Frequent Contributor
timestamp: October 26, 2016, 09:50:11 pm
content: While on the topic of logic iC's I have come across a schematic that uses a 74AC14 to buffer the output. Looking at the schematic I wonder how does a logic IC buffer a circuit. Obviously the 200 ohm in parallel puts it roughly into a 50 ohm impedance, but what do the hex inverting Schmidt do? One stage of the 74Ac14 will convert the sine to a inverted square wave, but what does sending it to the other 4 stages do in terms of buffering other than reinverting the signal?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 27, 2016, 12:54:12 am
content: Digitally speaking, absolutely nothing, just extra propagation delay.But digital is a subset of analog. What does it do to the analog signal level? What are the output pin characteristics of a single 74AC gate? Four in parallel (with resistors)? What does a pin even consist of?You'll need some materials to do your homework... See for example page 22 ofhttps://archive.org/stream/RcaAdvancedCmosLogicIcs74ac-74actfor useful information.Tim

author: Cliff Matthews
author_rank: Unknown
timestamp: October 27, 2016, 01:22:48 am
content: Quote from: PotatoBox on October 26, 2016, 09:00:38 pmThe entities mentioned don't sell products, they facilitate sales. In this case, mostly from China and you can linger till the night hours on this forum alone, reading all the threads listed under the search "ebay fakes"

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 27, 2016, 01:23:18 am
content: Quote from: ebclr on October 26, 2016, 03:10:21 pmTo be quite honest, I'm not interested too much in using arduinos and other micro controllers. Id much rather learn and build things with traditional IC's.

author: ebclr
author_rank: Super Contributor
timestamp: October 27, 2016, 01:54:31 am
content: Don't believe that everything is fake , that is not real, China have the biggest components market in the world and a lot of surplus, the ones that blame on fake are the ones that look for a 100 USD chip for 1 USD, I bought a lot of components from ebay and aliexpress and 0 problens, but i used all components on the typical engineering safe zone, i don't pull the piece to extreme.The point is quite simple, if you don't care about price, buy from some branded corporations like mouse , RS even the horrible digikey.If you like your pocket and aren't doing anything mission critical you can save a lot on both .

author: Paul Moir
author_rank: Frequent Contributor
timestamp: October 27, 2016, 02:08:01 am
content: Quote from: ebclr on October 27, 2016, 01:54:31 amJust a minor note on this you may not know: Digikey ships to Canada super cheap ($8) and super fast (1-2ish days). So they're not so horrible up here. Judging by their tracking, I think they're sending trucks up to Winnipeg and air freighting from there.

author: PotatoBox
author_rank: Regular Contributor
timestamp: October 27, 2016, 02:53:56 am
content: Quote from: ebclr on October 27, 2016, 01:54:31 amWhats wrong with digikey?

author: Bryan
author_rank: Frequent Contributor
timestamp: October 27, 2016, 05:29:37 am
content: Nothing as far as as I am concerned. I think they are great. Can't beat the $8.00 shipping for 1-2 day service.

author: tautech
author_rank: Super Contributor
timestamp: October 27, 2016, 07:45:50 am
content: Quote from: Bryan on October 26, 2016, 09:50:11 pmThat circuit's commonly seen as a DIY pulser:https://www.eevblog.com/forum/projects/super-simple-'fast-edge'-pulse-generator-for-scope-based-basic-tdr/Member w2aew did a couple or more vids on it, here's his #87 from another thread, quickly found using the forum's search for: 74AC14https://youtu.be/NuXitMK3HSA

author: Bryan
author_rank: Frequent Contributor
timestamp: October 27, 2016, 08:14:52 am
content: Thanks, forgot about that video. Allen does use a similar circuit in a further video, but still not really sure why ganging a number of Schmidt's in parallel acts as a buffer? I get the resistors in parallel as it will put it near 50 ohm impedance.https://youtu.be/9cP6w2odGUc

author: Bryan
author_rank: Frequent Contributor
timestamp: October 27, 2016, 08:28:49 am
content: Quote from: T3sl4co1l on October 27, 2016, 12:54:12 amThat is a very interesting e-book. thanks