Spurious triggering of 4013 flip-flop

Thanks again to the several here who made same suggestion. Did that a couple of days ago and pretty confident it will eliminate the spurious triggering.

However ... I still want to be able to switch the lamp from the shed as well as from the lounge. The issues of separate power supplies and earthing so far still elude me. So maybe I'll shortly post again with that new focus.

Terry, East Grinstead, UK

If you use a SPST relay you can pair it with a SPST switch to control the lamp like in a regular two switch light circuit.

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  When I tried casting out nines I made a hash of it.

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to reduce junk pickup? It might be all you need.

Your original drawing seems to have gone AWOL so it's hard to give further advice since I didn't commit it to memory. How did you switch the device in the shed?

Is it practical to use a radio remote to control the device from either loc ation? They are available on eBay at a very good price.

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  Rick C. 

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Do you mean a SPDT relay and switch?

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  Rick C. 

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Sorry, I must have accidentally moved it. Here's a new link:

However, as mentioned, it's now changed radically, so I'd ignore it. I'll probably redraw in a new thread. In brief though, the FF is now in the lounge, so when I press a key it supplies the toggled +14.5V from the RC Unit's power supply to the remote relay directly.

With the previous circuit I used an additional trivial circuit in the shed: another NPN (triggered by a push-button) to take the relay's -ve terminal (which is actually in the adjacent garage) to 0V.

Not really in this case, and I'm keen to keep it as simple as possible. More RC (radio rather than IR) would be way OTT.

It seems that the only simple way I can activate the relay from the shed is to take +13.3V from the shed's supply to the relay +ve, connecting both 0V rails. Both supplies are earthed, and that's been criticised by several up-thread.

Terry, East Grinstead, UK

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I think you are saying you wired a second transistor in parallel with the f irst so either device can turn on the relay and light, but they must both b e off to turn it off.

location? They are available on eBay at a very good price.

I don't follow how that would be over the top? Not MORE RC, replace the IR which has limited range and use one or two remotes to control the device i n the garage. I looked at remotes designed for garage door type control an d the receiver comes in a version which includes the FF. So one receiver, a transistor to control the relay and two remotes. Sounds pretty simple to me.

If the supplies are floating who cares? A simple way to control the light with a switch is to use a... switch across the relay contacts. You know, a wall switch... the kind they use to control lights.

--

  Rick C. 

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UK mains earthing schemes are not completely straightforward either, e.g.

You most likely have TN-C-S (PME as was) to your residence, which may also be required to be locally earthed to metallic water and gas supplies if it is recently modified and updated to be in compliance.

Depending on how far your shed is from your consumer unit, it may be expected to be earthed using a TT scheme (live and neutral only, with local earth rod/mat nearby) to be compliant. This improves safety local to the shed in case of faults but may introduce potential difference between locations which you have connected using other non-power cabling. Physically isolating them is best, as already suggested.

I'm going to bet you've got a bit of twin-and-earth cable strung up on poles or buried like it's 1959 though.

North America uses a TT-like scheme generally because power distribution is often medium voltage (12.5kV/7200Y) to the street with pole transformers for the 120V local loop for domestic consumers, so no substations to provide a protective conductor with the live(/line) and neutral.

I don't think you can have read several of my previous posts up-thread. For example, here's a link used in my discussion with Tom three days ago:

Summarising, my 20 year old IR RC Unit was a complex project and its

12-button keypad currently controls 10 different output circuits. For several of those, located outside the lounge, like my Garden Lamp, there are other inputs, such as dawn/dusk triggers, overrides, resets, local switches, etc. The Dining Lamp is another example.

So, ditching my entire RC Unit instead of a relatively trivial add-on to one of ten projects is hardly an option I would contemplate!

1. I expect that might be less flexible than electronic switching. Once back in the house I might want to toggle again.
2. Minimising both mains and DC wiring is a factor. As mentioned, the relay is in the garage (closer to the lamp) and its two controlling circuits are the lounge and the shed. I already have connections close to the relay for: RC Unit +15V, RC Unit 0V, Key 7 FF output for the Dining lamp (low impedance), Shed +13.3V, Shed 0V. I want to avoid further long wiring if possible.

Terry, East Grinstead, UK

Could you expand a bit on your point about 'floating supplies' please?

Terry, East Grinstead, UK

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IR which has limited range and use one or two remotes to control the devic e in the garage. I looked at remotes designed for garage door type control and the receiver comes in a version which includes the FF. So one receive r, a transistor to control the relay and two remotes. Sounds pretty simple to me.

Yeah, I definitely missed that one. I've never found a need for remote con trol of lamps and such unless it was added to the existing electrical circu it. The one case where I wouldn't mind having such a control would mean it would need to be a DPDT switch in an existing three way switching circuit in the basement. Then I could turn it off without being at a wall switch. Even then it would need is read out to indicate the light was on in the fi rst place.

It doesn't need to be tossed. What will you do when you run out of buttons anyway?

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ht with a switch is to use a... switch across the relay contacts. You know , a wall switch... the kind they use to control lights.

How do you plan to "toggle" the remote switch from the house? I didn't see your explanation of how you intend to connect it up. With the FF in the h ouse your shed switch doesn't have the option of switching that. You can m ake the relay a SPDT and add a three way switch so either one toggles the s tate of the light. Flexibility doesn't require electronic control.

I have no idea how fare anything is from anything else. I'm not sure what a "shed" is in the UK. They seem to be a lot more common than "sheds" here in the US. We mostly use sheds for storing tools and such. In the UK the y seem to be out buildings that are not heated, but occupied by people more so than tools.

Should I point out that an RF remote minimized all wiring allowing the rece iver to be in the garage? I've not seen RF remotes with 12 buttons (althou gh they may exist) but I have seen them with four. I'd say this is another good project to get around the wiring limitations of your current approach .

Power supplies can be connected to earth ground through the power connectio n or they can be isolated. When isolated they are referred to as "floating ". The only problem with using two supplies is if they are both grounded, creating a ground loop... at least in the US. I'm not sure how power circu its are wired in the UK, but I know it is usually different. If your shed supply is not grounded and is isolated from the power line, there is no gro und loop and there should be no hazard from the power line if the neutral o pens up. Most simple power supplies are isolated and floating.

I would also point out the use of an RF link lets each controlled device us e whatever power is most handy including solar.

--

  Rick C. 

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Or use another relay. Your IR receiver sends 14V to a signal relay in the shed In the shed contract closure is debounced and sent to the flip-flop which operates from shed power The flip-flop commands the power relay as it did originally

We were only suggesting opto couplers because they are cheaper and more reliable than relays, signal relays can be scrounged from old POTS modems, or you can use a power relay instead.

--
  When I tried casting out nines I made a hash of it.

yeah, sorry.

--
  When I tried casting out nines I made a hash of it.