Help needed with 4013 circuit

[glids]

G'day all,
I want to build a radio remote control for a GPO. (Reason: I have built a capstan winch to haul a caravan up my driveway, and want to be able to turn the winch on and off while I steer the van at a range of up to 35 metres.)

My neighbour has given me a radio remote unit (transmitter / receiver) which has more than enough range, and has an output signal of 3.6V, almost square wave, roughly 0.7 seconds long. The signal looks very clean on a CRO.

He also gave me the details on a CD4013 Flip Flop which should latch 'ON' or 'OFF' an output to a 240V relay, as set out in the attached circuit.

The circuit is not reliable.
We have tried a number of modifications - adding capacitors here and there around the 4013, changing resistor values etc, but nothing makes sense. Sometimes the unit will change output state, but not always. Sometimes it will change state and then immediately change back. Sometimes there is a noticeable delay before the change of state, but the 4013 should activate almost immediately on rising voltage input (from the radio output).

We cannot find anything wrong with the finished board. I even bought another 4013 and set it uo on a breadboard with minimal adjacent components - still no reliable operation.

Can any of you suggest circuit errors, things to try etc?

Thanks in advance.

cheers,
glids

 

[ericgibbs]

hi glids,

Looking at the drawing, you have a C/R filter on pin 11, the clk line.

The 4013 requires a clean, fast rising edge, to make it toggle.
If the clk edge rises 'slowly' the 4013 will switch erratically.
Also at 3.6Vs, its working close to its lower limit of 3V.

If you put your scope on pin11 [use +10 probe], you will probably see a slow clock edge.

Also scope the output of the 4013, when you send the trigger pulse, I suspect it will be rapidly switching during the clk edge period.

You may require a schmitt ic. something like a 40106 with a C/R filter, this should give you a clean edge.

EDIT: attached drawing.

Eric

 

[Gayan Soyza]

hi glids take a look here
https://www.electro-tech-online.com/threads/newbie-question-pulse-on-off-switch.24533/#post167524

But there is some noticable delay on that try & check it.

Here is another one I made no any propogation delay with this.But its with descretes.
**broken link removed**

 

[glids]

hi glids,

Looking at the drawing, you have a C/R filter on pin 11, the clk line.

The 4013 requires a clean, fast rising edge, to make it toggle.
If the clk edge rises 'slowly' the 4013 will switch erratically.
Also at 3.6Vs, its working close to its lower limit of 3V.

If you put your scope on pin11 [use +10 probe], you will probably see a slow clock edge.

Also scope the output of the 4013, when you send the trigger pulse, I suspect it will be rapidly switching during the clk edge period.

You may require a schmitt ic. something like a 40106 with a C/R filter, this should give you a clean edge.

EDIT: attached drawing.

Eric

Thanks Eric, and thanks for the modified circuit .pdf

All the circuits I have seen for the 4013 seem to have the RC setup on the input - even one in Gayan's reply has something similar (last one).

I think we already checked the input signal and I reckon it was fairly clean and fast. I will have a look at it (and the output) again.

The 3.6V input should not be the problem, we have got it to trigger at <2V (even though outside the specs).

The 40106 is another option, but it seems if you use one of them, you can use all of it to create the flip flop. I will consider it if I cannot get the 4013 to work.

cheers,
glids

 

[glids]

hi glids take a look here
https://www.electro-tech-online.com/threads/newbie-question-pulse-on-off-switch.24533/#post167524

But there is some noticable delay on that try & check it.

Here is another one I made no any propogation delay with this.But its with descretes.
**broken link removed**

Thanks Gayan,

I'm happy to go to discrete components if needed, I thought the 4013 would be a more compact / reliable way to do it.

cheers,

glids

 

[Roff]

Thanks Eric, and thanks for the modified circuit .pdf

All the circuits I have seen for the 4013 seem to have the RC setup on the input - even one in Gayan's reply has something similar (last one).

I think we already checked the input signal and I reckon it was fairly clean and fast. I will have a look at it (and the output) again.

The 3.6V input should not be the problem, we have got it to trigger at <2V (even though outside the specs).

The 40106 is another option, but it seems if you use one of them, you can use all of it to create the flip flop. I will consider it if I cannot get the 4013 to work.

cheers,
glids

Your clock filter has about a 22 millisecond risetime (2.2RC). The CD4013 requires that the input risetime be less than 15usec.
Philips HEF4013 has Schmitt trigger clock inputs built in.

 

[ljcox]

I agree with Ron

In addition, I can't see a bypass capacitor across the supply line.

You can observe odd effects if there is insufficient (or no) bypassing.

I suggest you connect a 100 nF between pins 14 and 7.

 

[glids]

still playing up!!

Hi guys,

We have tried a number of modifications to the original circuit, but not had any real success. Please bear in mind that I can follow (build) a circuit, but I only have a basic understanding of the processes involved and I cannot design circuit mods. My son-in-law understands the technology, but he works (I'm retired) and I've already tied up several nights trying to sort this out.

The output of the radio receiver normally only drives a very small beeper speaker, so we measured the output current of the receiver and it is very low - only around 0.7 mA (3.6V). Is this enough to trigger the 4013, particularly with the various resistors being introduced? It seems that whenever we introduce a resistor large enough to get the right time constant etc, we kill off the input signal to the 4013.

I wondered if a transistor (or similar) could go between the receiver output and the pin 11 input to increase the operating current. If this is possible, could anyone suggest a suitable type of transistor and a circuit.


Other notes:
1. Many of the 4013 circuits I have found on the 'net' use a switch to ground - we need to use the radio receiver output, either direct, or via a modifying circuit.

2. I would be happy to use discrete components rather than the 4013, but all the transistor flip-flop circuits I have found so far are activated by a switch to ground, rather than pulsing an input signal as we have from the receiver.


Many thanks for assistance so far.

cheers,
glids

 

[Roff]

Eric's mod using the 40106 should work. You will also need to connect +3.6V to pin 14 and 0V to pin 7 of the 40106. In addition, connect all unused input pins (5, 9, 11, 13) to 0V. Have you already tried this?
You have marginally enough gate voltage for your MOSFET. I would change the 220R (220 ohm) resistor to 270 ohms. This should make your supply voltage about 4V, which is the minimum voltage at which the MOSFET is specified. Also, change the 100k in series with the gate of the MOSFET to 100 ohms.

 

[glids]

done!!

Thanks for all you help guys.

I finally made the trip to Tricky Dickies and bought a 40106.

The circuit now seems to work reliably - all I have to do now is find enough room on the board for the extra chip.

cheers all,

glids

 

[ljcox]

Thanks for all you help guys.

I finally made the trip to Tricky Dickies and bought a 40106.

The circuit now seems to work reliably - all I have to do now is find enough room on the board for the extra chip.

cheers all,

glids

Tricky Dicky is generally rather expensive for electronic parts. I use Semtronics in Mitcham.

You could use (as Ron suggested) the Philips HEF4013a Flip Flop which has Schmitt Triggers on its clock inputs and therefore avoid the need for the 40106.

 

[ericgibbs]

Hi RonH,

Question regarding the Philips HEF4013B, is the schmitt trigger input for the clock a 'recent' upgrade?.

Just downloaded the latest HEF4013B which clearly shows and describes the schmitt on the diagram.
My earlier data sheets show it as a standard input, no mention of the schmitt.

I have a number of the 'older' HEF4013B on the shelf, Im wondering if they now maybe obsolete.

Eric

 

[Roff]

Hi RonH,

Question regarding the Philips HEF4013B, is the schmitt trigger input for the clock a 'recent' upgrade?.

Just downloaded the latest HEF4013B which clearly shows and describes the schmitt on the diagram.
My earlier data sheets show it as a standard input, no mention of the schmitt.

I have a number of the 'older' HEF4013B on the shelf, Im wondering if they now maybe obsolete.

Eric

Eric, I don't know the answer. The only way I knew that was from a thread a couple of years ago. IIRC, someone was having similar clock risetime problems, and someone (the OP?) discovered that some brands worked and some didn't. I seemed to recall it was the HEF part, so I looked at the datasheet. I have no idea if this is a relatively new development, or if they have always been that way.