Need a flip/flop bistable with following features. Q and not Q must change states upon each positive input pulse. I have tried both a 4013 and 4027 b ut some crazy reason can't seem to get the desired results. I know it shoul d be real simple but solution eludes me. HELP!!
Firstly, you need a logic-level 'input pulse' source. Then. you need to power the flip/flop chip, with a bit of power supply bypass capacitance (.01 uF or more) near the chip. Then, the unused inputs (Set, Reset, for both sections , and D and CLK for the unused section) must be connected to keep them quiescent. Connecting those all LOW will be fine. Then, connect your input pulse to CLK and connect D to /Q for the active flip/flop section of the CD4013.
That's not the complete list of things to worry about, but it's a good start.
All those options have been tried including buffered outputs, different IC's, etc. Will keep digging. Almost to the point of just trying a discrete symmetrical bistable with appropriate out put sections.
put a pull down R on the clk input pin, something like a 5k to 10k etc..
connect the Data input to the Q/not output..
You may want a small cap on the clk input going to common to slow down the respnse, otherwise it may look erratic.
This is assuming you are using some switch or jumper as the input signal. (deboucing).
Never put more than the VCC/VDD supply voltage on the inputs
Jamie
The clock signal must have a fast risetime, going from under V/3 to over 2V/3 in under 15 us (at 5V power); it has to stay high or low for 250 ns or more.
What DOES happen? What is the output state, and does it change? How are you loading the outputs? Driving the inputs?
Hmm, you wouldn't by any chance be breadboarding this on one of those white plastic proto-boards with a bazillion little sockets on 0.1 inch spacing, would you?
If so, besides what others have suggested, try adding a 10k series resistor to the clock line of your 4013. Many years ago I had exactly your problem, until I eventually stumbled onto the magical 10k resistor trick.
You don't need it when you actually build the circuit on PC board, only when all the chip lines are cross-coupled by the capacitances between the proto-board connectors. Slowing down the rise time just a smidge with the 10k seems to do the trick.
Best regards,
Bob Masta DAQARTA v8.00 Data AcQuisition And Real-Time Analysis
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I think you nailed it. The proto board is rather large due to amount of cir cuitry I have associated with it. I was having problems with a 555 as well that I had not noticed or mentioned in my previous post. Started over with the 555 and was finally able to get it working. It is also possible I might have some bad IC's as well. Bought 5 in a tube from Mouser. Will definitel y take your and others advice. Filtering seems to be extremely important wi th the 4013. That puppy is very fast. Thanks for the input.
What behavior are you actually seeing?
Another suspect is a poorly terminated clock line that's ringing and clocking the chip multiple times each edge, but without knowing your setup I can't say.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Probably needs to make sure \S\ and \R\ are tied high >:-}
OR... too slow a clock edge. ...Jim Thompson
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Problem solved. It indeed appears to have been induced noise. Capped the he ll out of everything and it settled right down. Apparently my first attempt at capping it was not sufficiently robust. Thanks for everyone's help. Wil l post pics of the Beast (redneck version of a Mighty Mule) when we are don e.
Hehe!!
100 ns rise.
That should be a good speed for 4000 series logic. Maybe on the edge of acceptability for 74HC4000, and very possibly too slow for 74AHC.
Can you choose the free hosting service that you distrust the least and post both a schematic and a photo of your actual physical circuit? Chances are that there's something going on here that's beyond what they mention in the data sheets.
-- www.wescottdesign.com
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Everything stabled up after addition of caps in the right places. Circuit i s not finalized as of yet. It is a controller for a homemade gate opener ak in to a Mighty Mule only over-killed to all dickins. Basically it is a wire less momentary receiver feeding 555 for pulse shaping then flip flop for bi stable outputs each of which feeds 555 providing timed output to run a moto r (1 555 for each direction) plus appropriate power/polarity handling. The motor is limited via both diode steering as well as timer disables derived from said closures. We are using a 2200 lb. capacity linear actuator (OVERK ILL but it was free)so if it ever gets to an end stop it will tear stuff as under. It is made for 24VDC. We are using it on 12VDC which takes some of t he power away but not by much. It will push me right off the floor. So ther efore the double limits. Will post a schematic and pics once it is further along. Hope to have circuit nailed down by end of weekend. By the way. Does anyone know how to render a jpg or gif from TinyCad?
I don't know anything about TinyCad, but ALT+PrintScreen will copy the image to the Windows Clipboard as a bitmap, from which you can paste it into Windows Paint and save as JPG or GIF (or PNG, etc).
Best regards,
Bob Masta DAQARTA v8.00 Data AcQuisition And Real-Time Analysis
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is not finalized as of yet. It is a controller for a homemade gate opener akin to a Mighty Mule only over-killed to all dickins. Basically it is a wi reless momentary receiver feeding 555 for pulse shaping then flip flop for bistable outputs each of which feeds 555 providing timed output to run a mo tor (1 555 for each direction) plus appropriate power/polarity handling. Th e motor is limited via both diode steering as well as timer disables derive d from said closures. We are using a 2200 lb. capacity linear actuator (OVE RKILL but it was free)so if it ever gets to an end stop it will tear stuff asunder. It is made for 24VDC. We are using it on 12VDC which takes some of the power away but not by much. It will push me right off the floor. So th erefore the double limits. Will post a schematic and pics once it is furthe r along. Hope to have circuit nailed down by end of weekend. By the way. Do es anyone know how to render a jpg or gif from TinyCad?
Slight delay on posting a schematic. Well as usual got in hurry and over am bitious. Stuffed board too full and 556 caught a short and nuked itself. So sad watching that little puff of smoke shooting like a miniature pyro devi ce out of the side of the 556. At least I got a small pyro hit from it. Gri n!! Onward.
-- Low for a 4013. :) John Fields
The little smiley face kind of gave the joke away. I thought it was funny.
A 4013 will act as a bistable if you run the NOT-Q back to the D input, whatever logic state is on NOT-Q/D input gets clocked through to Q on the CP positive edge.
Whatever flip-flop you use, problems can arise from a glitchy CP, sometimes it can help to feed CP via a C/R differentiator.
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