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- Joined
- Jan 21, 2010
- Messages
- 25,510
It certainly does relate to your thread.
What I was expecting was parallel connections in alternate pairs. Something like this:
Code:
+--------------------------------- A
| ----------------------------+
+--------------------------- |
| ----------------------------+
+--------------------------- |
| ----------------------------+
+--------------------------- |
B ----------------------------------+What you have is a continuous track between A and B
Code:
A--------------------------------+
B--------------------------+ |
| |
+-----------------------+ |
| |
+-----------------------+ |
| |
+-----------------------+ |
| |
+-----------------------------+As you will have gathered, I am not qualified to comment upon that, regrettably. However, I can say that the device has worked well and has not suffered any modifications. However, upon close examination it appears as though your first diagram is nearer the truth.
In layman's terms, there appear to be what I will call prongs, as in the prongs of a fork. These prongs form a maze-like structure with alternating prongs leading to one of two terminals. I believe this is what you mean to describe in your first diagram.
My problem, happily, does not lie in this area. It is simply that the two grub screw connectors at one corner of the board have become so corroded that I cannot shift them and am therefore unable to connect fresh wires.
As you know, one of your number has kindly agreed to help and I am awaiting his next communication.
Shunhook
In layman's terms, there appear to be what I will call prongs, as in the prongs of a fork. These prongs form a maze-like structure with alternating prongs leading to one of two terminals. I believe this is what you mean to describe in your first diagram.
My problem, happily, does not lie in this area. It is simply that the two grub screw connectors at one corner of the board have become so corroded that I cannot shift them and am therefore unable to connect fresh wires.
As you know, one of your number has kindly agreed to help and I am awaiting his next communication.
Shunhook
- Joined
- Nov 28, 2011
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Steve, I don't see it the way you've drawn it. To me, the diagram in post #19 has two sets of interlaced fingers, as Shunhook described. The ones that enter from the left connect through the track at the bottom to the connection point at the bottom right. The ones that enter from the right connect to the connection point half way up, or another connection at bottom right, next to the first one. (The picture is too blurry to be sure.). The blob at the top must be non-conductive, whatever it is.
Shunhook, if you're waiting for more information from me... I've been hoping that someone else could advise on weatherproofing. All I can suggest is that you try to loosen the stuck screw with some light machine oil, or a CRC product like WD-40, 2-26 or 5-56. Once you've removed the screw you may be able to clean the contact using emery paper. When you reconnect the wires, you may want to cover the whole connection area, including part-way up the outer insulation of the wire, with a weatherproofing substance like silicone sealant or silicone rubber.
A close-up in-focus picture of the connection area might help us.
Shunhook, if you're waiting for more information from me... I've been hoping that someone else could advise on weatherproofing. All I can suggest is that you try to loosen the stuck screw with some light machine oil, or a CRC product like WD-40, 2-26 or 5-56. Once you've removed the screw you may be able to clean the contact using emery paper. When you reconnect the wires, you may want to cover the whole connection area, including part-way up the outer insulation of the wire, with a weatherproofing substance like silicone sealant or silicone rubber.
A close-up in-focus picture of the connection area might help us.
Kris, Thanks for your message. I am not waiting for advice on weatherproofing. I'm afraid that loosening the screws is out of the question - better men than me have tried and failed. The danger is that exerting too much force will wrench the connector from the board with disastrous results. I guess that it might be possible for some expert with a soldering iron to detach the connector and replace it. I will try to get a better pic, but your description of interlaced fingers is admirable. Wish I'd thought of it.
- Joined
- Jan 21, 2010
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- 25,510
Hahahah
I just realised what I did.
I confused the tracks with the spaces between the tracks.
They are interleaved fingers.
- Joined
- Nov 28, 2011
- Messages
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I did the same as Steve. Apparently the dark lines are the actual tracks of the board, not the lighter parts. That way it makes sense.
As a machinist, here's how I see the screw and weather issues: You could try holding just the block with the screws in it with a vise, locking pliers or adjustable jaw pliers so no force is exerted on the board when you're trying to loosen the screws. Failing that I would ask Dave to solder in a new wire terminal for you.
Another suggestion for after you have fixed the screw seizing or replaced the terminal block is to liberally coat both the screw threads and screw holes with anti-seize compound...you should be able to get it at any auto parts store. You may also want to use silicone to secure a small plastic box or similar cover over the terminal so that it keeps the weather off of the screw connections. Seal the openings of the box where the wires exit also, so that there are no openings for water to get in. Just blob it on there good. Alternatively to the box, you could just coat the entire terminal block with silicone, but if it ever needs servicing again, it will be much more of a pain to get off than the little cover.
Make sure if you go this route that you get silicone rated for outdoor use.
As a machinist, here's how I see the screw and weather issues: You could try holding just the block with the screws in it with a vise, locking pliers or adjustable jaw pliers so no force is exerted on the board when you're trying to loosen the screws. Failing that I would ask Dave to solder in a new wire terminal for you.
Another suggestion for after you have fixed the screw seizing or replaced the terminal block is to liberally coat both the screw threads and screw holes with anti-seize compound...you should be able to get it at any auto parts store. You may also want to use silicone to secure a small plastic box or similar cover over the terminal so that it keeps the weather off of the screw connections. Seal the openings of the box where the wires exit also, so that there are no openings for water to get in. Just blob it on there good. Alternatively to the box, you could just coat the entire terminal block with silicone, but if it ever needs servicing again, it will be much more of a pain to get off than the little cover.
Make sure if you go this route that you get silicone rated for outdoor use.
Last edited:
- Joined
- Nov 28, 2011
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Good advice, eKretz.
A new terminal block purchased from R.F. Potts, Derby for £0.20 Fitted and posted today.
The board has interdigital tracks and needs a quarter of it to be wetted to work. The resistance is then about 100k.
The circuit uses a 7555CN (CMOS 555), 2 transistors and a sounder. Battery is 9V PP3, 6LR61. It beeps about once a second.
I cannot measure the current drain when not sounding. It is about 20mA when sounding.
The board has interdigital tracks and needs a quarter of it to be wetted to work. The resistance is then about 100k.
The circuit uses a 7555CN (CMOS 555), 2 transistors and a sounder. Battery is 9V PP3, 6LR61. It beeps about once a second.
I cannot measure the current drain when not sounding. It is about 20mA when sounding.
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- Nov 28, 2011
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I'm not surprised about the extra tracks. I was trying to picture that board with a raindrop on it... it wouldn't be able to bridge those tracks; they're too far apart!
Is it just bare copper?
Kris
I do not know whether it is plain copper, it is quite brown and there is a white stripe on it, I thought it was pigeon poo but it would not come off with a plastic scrubber so it is probably paint.
I did not want to rub the tracks down to bright metal.
shunbrook
I made an inverter/capacitor discharge ignition many, many years ago.
Duke
I do not know whether it is plain copper, it is quite brown and there is a white stripe on it, I thought it was pigeon poo but it would not come off with a plastic scrubber so it is probably paint.
I did not want to rub the tracks down to bright metal.
shunbrook
I made an inverter/capacitor discharge ignition many, many years ago.
Duke
- Joined
- Jan 21, 2010
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- 25,510
shunhook, I have moved your new question to a new thread here: https://www.electronicspoint.com/electronic-ignition-help-t260975.html
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