Still Gropping In The Dark! Repeat Timer Circuit

[Shaka]

Hey! I am new to all this but seriously catching on... Just built this repeat timer circuit from ... http://www.reuk.co.uk/Repeat-Timer-Circuit.htm everything seems to be working fine, except that the relay wont charge, even though it’s getting 11.78Volts.

I have looked the diagram and my prototype over to ensure I did everything I was supposed to – still no Joy!
well the Led flashes, the 555 is powered after 20mins, but the relay wont switch on...

My question now is:-
1. Can I use any NPN Transistor for the 555 circuit (I used a 547B)?
2. Is there a generic (multipurpose) value i should be looking for?
3. I don’t know if this is the problem but I seem to be reading two positive reading on both terminals of the relay coil (even with the relay disconnected)

Someone please help.

[billhowl]

In the circuit, the relay should connect directly to 12V supply, because 4060B CMOS binary counter can only source out 6mA. refer this datasheet
http://focus.ti.com/lit/ds/symlink/cd4060b.pdf

As for for the 547b transistor, it can only supply 100mA so your relay should draw less then 100mA.
http://www.datasheetcatalog.org/datasheet/mcc/548B.pdf

[Soeren]

Hi,

There's an error in the circuit. It has to be like this:

[Shaka]

Thanks Guys, I was begining to worry .... while I try the 2 suggestions out, I still have some issues.

In the circuit, the relay should connect directly to 12V supply, because 4060B CMOS binary counter can only source out 6mA. refer this datasheet
http://focus.ti.com/lit/ds/symlink/cd4060b.pdf

So if I connect the Relay directly to the power source, how do i ensure it only triggers at the end of 20mins?

As for for the 547b transistor, it can only supply 100mA so your relay should draw less then 100mA.
http://www.datasheetcatalog.org/datasheet/mcc/548B.pdf

So what value of should I be looking at? Will be looking out for your response.

[Shaka]

For Soren,
The 4060 is meant to trigger the 555 after a set time (set by the Resistor and Cap on the 4060B) - in this circuit it controls the "off time".

Pin 3 of the 4050 is high at the set time, therefore powering the 555 which controls the "On time" (set for one min by the resistor and cap attached to the 555).

If I connect the 555 straight to the 16th pin of the 4060B - it means the relay will be triggered at startup (instead of waiting 20 mins).

But for avoidance of doubt I will test it and post back my findings. Thanks

[Shaka]

Still no joy, tried as directed.

I think the problem should be from the Pin 3 output end, both leads go to positives, and i wonder why the 555 output seems to bypass the relay to the ground...  perharps i should loose the transistor alltogether and ground one end of the relay.

Its sucha shame when ppl post schematics they are not willing to support. Still hanging in here, hopefully someone will have a clue.

[billhowl]

So if I connect the Relay directly to the power source, how do i ensure it only triggers at the end of 20mins?

the Relay only triggers when application of a negative trigger pulse to pin 2 of 555 Timer.

So what value of should I be looking at?

so if your relay only draw less then 100mA that will okey.

The 4060B pin 3 will start with 20mins OFF times and the Pin 3 of 4060 will be low at 0V and the 555 Timer will not trigger.
In the next 20mins ON times, the 555 Timer still will not trigger because the Pin3 of 4060 is in positive trigger pulse.

The 555 Timer will trigger when at the end of the 20mins ON times and it go to OFF times and the relay should turn ON for one min.

So you should connect as show by Soeren the top line of the 555 Timer circuit to Pin 16 of 4060B

Can you update the what have try and not working?

4.1 be patient.
people post here for fun. if you want to remind people about your topic after a suitable period of time that is fine (and sometimes recommended, it's easy to forget about that post you meant to reply to...) but try to include an update on any progress you have made or other things you have tried since the first post.
simply posting "really i need help!!!!!!" six hours after your first post with no additional information is just rude.

How to ask a questionhttp://www.societyofrobots.com/robotforum/index.php?topic=1480.0

[Shaka]

Thanks Billhowl,
No harm intended, I didnt mean to be rude (sorry if it came across like that). I was refereing to site where the circuit was published (http://www.reuk.co.uk/Repeat-Timer-Circuit.htm) in the last paragraph of my post, not this site. I am greatful for the help Iam getting here.

I moved the top line (without d 555 pin 2) to Pin 16 on 4050B, then connected the 555 pin 2 to pin 3 of the 4050B.) but this did not give the desired result of 20 Mins off, 1 min on, 20 mins off, 1 min on, etc. But your explanation suggests i should have monitored it beyound the first 40mins to get the real effect. So i will try that and fill you in.

Thanks.

[Soeren]

Hi,

The 555 will start a timing period each time its pin 2 is pulled low and since the 4060 will pull it low initially, it will start with a timing period - is that a problem?  (If so, we'll fix that).

On second thoughts...
Since the 4060's pin 3 will be low for longer than the timing period, you need to change the circuit a bit (nothing extraordinary).
Place a resistor (47k to 100k) from 555 pin 2 to V+ (555 pin 8/4060 pin 16) close to the 555.
Place a cap (1nF to 10nF) from 555 pin 2 to the 10 kOhm resistor going to pin 3 of the 4060.
This way the 555 will only see a brief trigger pulse and should work as intended.

[Shaka]

 I tried testing the circuit for longer that 1Hr to test the High Low sequence of the 4050 and 555. The 555 never came on even though the 4050 pin 3 did (every 17mins = 34 odd mins to trigger the 555)

Frustrated, I decide on a different thing, I removed the entire 555 part of the circuit and replaced it with one I found on the 555 datasheet (set for 1 min). It now works fine, except that it sends less than 12Volts so my 12Volts relay didn't charge - so I have bought a new 6 Volts one to handle the timer pulse, and then switch a bigger 12Volts on.

@ Soeren
Considering that relays are mechanical and may fail anytime - Perharps you can help me with a sketch of what you want me todo, cos I will rather have one relay to do the job than labour 2 relays (one small one to work with the switch, and a bigger 8 pin one to switch the poles for my motor. What do you think

[Soeren]

Hi,

Considering that relays are mechanical and may fail anytime

Calm now... Relays are very sturdy and well proven devices - millions of them have been handling all telephony worldwide not so long ago and the earliest mainframes used relays for logic (thousands and thousands of relays had to function reliably together or the "program" puked), just to give you an example of how "fragile" they are.
I have never had a relay fail on me (the driving semiconductor on the other hand...).

I drew up a couple of schematics for you yesterday (one with the 555 and one entirely CMOS4k), I'll probably get time tonight to finish them (component values and PCB-layout) and post them.

[Shaka]

cant wait to see what you have designed cos,for some reason, the 4060 pin 3 gets high at the right time, sends positive current to the 555, but the leds light up but still cant charge the relay. When I tested thow much current is flowing - its a mere 4Volts plus - so  think the 555 is draining all the power from the battery when it comes up.Thanks... like I said, I am not an expert.

[Soeren]

Hi,

When I tested thow much current is flowing - its a mere 4Volts plus - so  think the 555 is draining all the power from the battery when it comes up.

First up, current is measured in A (amperes), voltage is measured in V (volt).
It's most likely a question of either impedance or a wiring error of some sort.

I have this file http://That.Homepage.dk/PDF/Long_Interval_Timer_01.pdf for you now, One of the circuits needs going over with fresh eyes and the other still lacks quite a bit (dozed off over the PC and now I have to catch some Z's).
I put in a random relay, but since the relay is probably something I don't even have pad's for, it would perhaps be better to mount it off the PCB - what relay do you have?

[Shaka]

Wooow! This is wonderful. I wasnt expecting anything this proffessional. I will get on it right away. I called my local (Abuja, Africa) store and they dont have the CMos 4093 - looked it up on Radioshaks site too without luck. So I guess I might need to wait for you to finalize the 555 one.

You wanted to know what relay I was using... its a SMV 12 C with 6 contacts (8 pins) rated 5A 240V, I also bought a smaller 6Volts one with 2 contacts (5 pins).

Thanks Bro! this must have taken a long long time to put together.

[Soeren]

Hi,

I called my local (Abuja, Africa) store and they dont have the CMos 4093 - looked it up on Radioshaks site too without luck.

Strange, it's a very common IC, but the RatShack has gone bad.
Mouser's got plenty: http://dk.mouser.com/Semiconductors/Logic-ICs/_/N-4s5z6?Keyword=4093&FS=True
But it must cost a fortune in shipping to Abuja.

So I guess I might need to wait for you to finalize the 555 one.

Here it is: http://That.Homepage.dk/PDF/Long_Interval_Timer_02.pdf
Anyone spots a mistake, please say so.

You wanted to know what relay I was using... its a SMV 12 C with 6 contacts (8 pins) rated 5A 240V, I also bought a smaller 6Volts one with 2 contacts (5 pins).

I can't find anything on this relay. Do you have a link to a datasheet?
For now I just made it with the relay off-board. It's best to have a diode right on the relay terminals, to stop noise emitted by the fly-back pulses.

Thanks Bro! this must have taken a long long time to put together.

You're welcome - that's what I do to wind down after a hard day

[Shaka]

Thanks Soren,
I eventually got the IC at place in Lagos - they shipped this morning, should be here tomorrow.

I printed and etched the PCB over the weekend. It was my first PCB, and it went really well. Will drill the holes and solder as soon as the components arrive. Will keep you posted.

[Shaka]

Hey! I finally got the components, and soldered them - except for the 10nan cap, Couldn’t find one so I used a 15nano cap - see attachment.

Everything worked well, I tested each weld as I soldered - when I connected it up to the Battery, the RED led flashes, and I can adjust the cycle time (the led is an indicator of the timing) - but nothing seems tp happen at the other end. Pin 3 starts high - but the relay does not charge. I left it on for a long long time (I slept off after about an hour) to see is the relay will come on, but it didn’t.

My question now is what should I expect? have I done something wrong? Is the 10 -15 nano disparity too wide for the right effect?

[gaurav.p]

gr8 job

[Soeren]

Hi,

Hey! I finally got the components, and soldered them - except for the 10nan cap, Couldn’t find one so I used a 15nano cap - see attachment.

That's fine, no problem arrives from that.

Everything worked well, I tested each weld as I soldered -

Did you test the PCB with an ohm-meter?
In the photos, it seems like you over-etched a bit, although it's hard to judge from the small pics, so did you ensure that there is continuity where needed? Like, is there continuity from IC1 pin3 to IC2 pin2?

when I connected it up to the Battery, the RED led flashes, and I can adjust the cycle time (the led is an indicator of the timing) - but nothing seems tp happen at the other end. Pin 3 starts high - but the relay does not charge. I left it on for a long long time (I slept off after about an hour) to see is the relay will come on, but it didn’t.

My question now is what should I expect? have I done something wrong? Is the 10 -15 nano disparity too wide for the right effect?

For testing, you could (carefully) bend up IC2 pin2 and IC1 pin14 so that these pins don't go into the sockets and then connect them with a loose wire.
Then the IC2, the monoflop, should be triggered each 16 flashes of the LED and save you some waiting time (If it hasn't timed out when a new pulse arrives, nothing's gonna happen).

What happens at IC2 pin 10 when IC1 pin3 goes low?
Please measure and report the following points when power is on.
IC1: Pins 1, 4, 5, 10.
Q1 base

The 15nF is quite fine and don't worry, together we can troubleshoot the circuit.

[Shaka]

Thanks Soeren,
I looked everything over with a magnifing lens... and just like you said, there was a break in the line to the Transitor and also one burnt out diode.

Sorry!!! I should have seen that earlier, but thats what you get when you are teach a "green horn" like me.

Okay. now everything is working fine - testing with a multimeter, the IC2 sends 11.78 volts to the relay terminals for 30 seconds when I apply power, and it repeats again at exactly 31Mins later.

However, after putting the relay together, I noticed another problem. the relay remains charged long after 30 seconds - I realised that after 30 seconds, IC2 only drops the voltage from 11.78Volts to about 5.54Volts. I guess this is still enough to keep the relay energised.

New questions now are; Is there a way to cut it (or reduce it such that would not charge the relay) off altogether after 30secs?

Could this be becourse I used a secondary relay (I am driving a motor with this circuit) thst shares the same power source with the timer?

Woow! I bellieve that I (with your help) could put this together...

[Soeren]

Hi,

However, after putting the relay together, I noticed another problem. the relay remains charged long after 30 seconds - I realised that after 30 seconds, IC2 only drops the voltage from 11.78Volts to about 5.54Volts. I guess this is still enough to keep the relay energised.

What voltage can you measure (relative to B-) on the transistors collector (the pin going to the relay) when IC2 pin10 is high and when it's low?

New questions now are; Is there a way to cut it (or reduce it such that would not charge the relay) off altogether after 30secs?

It should, we just need to locate the reason why it doesn't.

Could this be becourse I used a secondary relay (I am driving a motor with this circuit) thst shares the same power source with the timer?

R6/C5 is a filter that should isolate the ICs from the noise that the relay introduces on the power line.
What do you mean by a secondary relay?

How much current does the relay take when energized?

[Shaka]

I should have posted a reply since Saturday - but I did something stupid so I couldnt run your test until now.

What I did wrong?
Perharps someone will learn from my mistake. I set the board down on the table top - I didnt realise that there where copper shavings on the table, flakes of solder. When I applied power, there was a small spark and I noticed the two diodes had burnt out.

I have just bought two new ones, will post a reply to your questions as soon as I test them.

Sorry Guys, you have to be patient with me - "Green Green Horn"

[Soeren]

Hi,

Any progress yet?

[Shaka]

Sorry Guys,
I got shipped out to Manchster - I have not been able to test the circuit until i return to Africa... and that might be a while. But I will be sure to post it right here. I am sure it should work, just that I am new to electronics and might have made some mistakes somewhere.