Need Help Finding a chip...BiStable Multivibrator (Dual, Quad, or Octal) - Page 1
Forum section: electronics / beginners

author: Falcon69
author_rank: Super Contributor
timestamp: September 18, 2014, 10:40:29 am
content: I would like to find a chip that does this, in a single package, Maybe even a quad...Octal would be awesome if they make one.It's a BiStable Multivibrator using transistors (though, in the chip, can be whatever). I just want the way it functions.Any Ideas?All I can find are Monostable Multivibrators, and SR Flip Flops don't seem to work right when both inputs are low. If I can find something like this in a chip that is quad or octal, it would save ALOT of room on the board for this circuit I'm designing.

author: Dago
author_rank: Frequent Contributor
timestamp: September 18, 2014, 10:59:30 am
content: Somebody has to say it again: why not use a microcontroller? Commence arguing about microcontrollers...

author: rs20
author_rank: Super Contributor
timestamp: September 18, 2014, 11:07:36 am
content: An SR flip flop is, indeed, bistable. If you're having issues applying a SR flip-flop to your application, please provide more details. Also, a 555 timer can be pressed into service as a bistable (or monostable, or astable) "oscillator", 556 is a dual 555.

author: Precipice
author_rank: Frequent Contributor
timestamp: September 18, 2014, 02:16:23 pm
content: Quote from: Dago on September 18, 2014, 10:59:30 ambecause a 74HC14, 6Rs, 7Cs would be cheaper and take less design time if you want 6 channels?Getting that many arbitrary oscillators out of a micro might mean you want real timers, and quite a lot of them, which means the supercheap ones are out. (The 74HC14 is going to be painfully prone to injection locking or other interference effects, mind).Of course, some kind of a hint of desired frequency, levels, tolerances would reduce the wild-assery of these guesses...Edit: I read bistable as astable. This answer isn't useful. Sorry.

author: tggzzz
author_rank: Super Contributor
timestamp: September 18, 2014, 02:43:02 pm
content: Quote from: Falcon69 on September 18, 2014, 10:40:29 amSo a bistable multivibrator might solve your problem.You will get better informed answers if you state your problem and any relevant parameters.

author: Falcon69
author_rank: Super Contributor
timestamp: September 18, 2014, 08:46:57 pm
content: Would a CD4044B work?http://www.mouser.com/ds/2/405/schs041d-204709.pdfBasically, I'm trying to make a latched circuit without using an SCR or transistors. Trying to keep power consumption low, and the SCR (in simulation) i just can't get to work.Input A goes from low to high (momentary Switch), Q goes to high and stays High, regardless of if the switched goes to a high state again, until Input B goes from Low to high (momentary switch) then Q goes back to low.The CD 4044B is a quad, which would be okay, the ones below or octal, which would be perfect, if they work.I can't find an LTSpice library file for it. I don't how to simulate it. I tried to simulate it in the very simple simulator, Falstad Circuit Applet, but I don't know what that one symbol is on the data sheet. Looks like an inverter with another connection coming from the bottom of it.I don't have a clock input, just simple analog ins and out.I also found these as wellhttp://www.mouser.com/ds/2/302/74HC_HCT573-225088.pdfhttp://www.mouser.com/ds/2/308/MC74LCX373-D-78576.pdfhttp://www.mouser.com/ds/2/302/74HC_HCT373-224946.pdfThere's more similar ones also.

author: Falcon69
author_rank: Super Contributor
timestamp: September 18, 2014, 10:07:25 pm
content: Is this what that inverter looking symbol with another input/output on the schematics is?If so, is there a way to replicate it with symbol components so I can put together a circuit in the Falstad Simulator to test the 74HC373?

author: timb
author_rank: Super Contributor
timestamp: September 18, 2014, 10:34:47 pm
content: A 555 can be used as a bistable multivitamin. Have you looked into that?Sent from my Smartphone

author: Falcon69
author_rank: Super Contributor
timestamp: September 18, 2014, 10:36:59 pm
content: yes, the problem is, the 555 is a very large chip. I am looking for an alternative to remove several passive chips, traces (ground/power), and lower the footprint size of the amount of IC's.I don't know how to deal with microcontrollers, that is out of the question. For the last month, I've been trying to find easy to learn tutorials on them, and I just can't understand them.

author: SArepairman
author_rank: Frequent Contributor
timestamp: September 18, 2014, 11:26:08 pm
content: Quote from: Falcon69 on September 18, 2014, 10:36:59 pmthis is like prison dude don't show weakness, before you know it you will be buying a Arduino

author: timb
author_rank: Super Contributor
timestamp: September 19, 2014, 01:05:19 am
content: Quote from: Falcon69 on September 18, 2014, 10:36:59 pmAh, well I can put you in touch with my ex who's bipolar, unstable and owns multiple vibrators, if that helps? Not quite the same thing though, I guess. (Plus she has a *very large* footprint.)Sent from my Smartphone

author: Falcon69
author_rank: Super Contributor
timestamp: September 19, 2014, 01:12:34 am
content: with that resume, she sounds like such a catchI've been reading up on the picAXE. It looks like for my circuit, I can use that, along with ULN2803 to control the LED's and a couple of enable input voltage regulators to control the high side switching.The ULN2803 takes up to 500mA per output, so that is more than enough for the LED's.I'm still confused though on the programming. When it says to read analogue input value, and based on the voltage value, send pin C.1 high (for example). But the values are just straight numbers, like 50. Does that stand for 50mV or 50volts?I understand that for seconds, 1 second real time equals 1000 for the value.I might need to start a new thread for this.

author: Hardcorefs
author_rank: Regular Contributor
timestamp: September 19, 2014, 02:01:08 am
content: Quote from: Dago on September 18, 2014, 10:59:30 am1 Board area2 Need firmware/development cycle3 Need physical loading4 Not parallel processing (despite what you have heard)5 slow

author: rs20
author_rank: Super Contributor
timestamp: September 19, 2014, 06:46:49 am
content: Quote from: Falcon69 on August 03, 2014, 05:03:50 amQuote from: Falcon69 on September 18, 2014, 10:40:29 amQuote from: Falcon69 on September 18, 2014, 08:46:57 pmI mean this in the most constructive way possible, but consistently your messages say "I tried using <thing that is perfectly applicable to purpose> and I just couldn't get it to work." I humbly suggest that you need to develop the skill of debugging. If an SCR isn't staying on when you think it should, check the datasheet. Look at the current running through it once it's triggered, is it more than the holding current? Work your way down until you find a contradiction. The thing is, you'll never find a contradiction. You'll say, "aha, whoops" and see what you've done wrong. If you're really stuck, post a message on the forum saying "I tried using an SCR, but when X happens, Y should happen, but Z. Here are the measurements I've made so far, and how I made them." And someone will tell you what's wrong.Just throwing up your hands and trying a totally different component is just absolutely not how you do engineering.

author: amyk
author_rank: Super Contributor
timestamp: September 19, 2014, 12:35:22 pm
content: Quote from: Falcon69 on September 18, 2014, 10:36:59 pmDefine "very large". You can easily get 555s in SOIC or VSSOP. Bare die (~1.3x1.7mm) are also available if even those are not small enough.

author: coppice
author_rank: Super Contributor
timestamp: September 19, 2014, 04:36:51 pm
content: If you don't like RS flip-flops you won't like the circuit in your schematic. Its the classic representation of an RS flip flop.

author: David Hess
author_rank: Super Contributor
timestamp: September 27, 2014, 03:10:02 pm
content: Quote from: Falcon69 on September 18, 2014, 10:40:29 amSet-reset flip-flops may or may not work depending on the design and technology. TTL will oscillate or misbehave with -set and -reset held low but with a CMOS implementation using transmission gates, this is actually a valid state.Maybe J/K flip-flop could be used.

author: 22swg
author_rank: Frequent Contributor
timestamp: September 27, 2014, 06:14:49 pm
content: 74LS123