Installation of Remote Switch

We have a number of fans in our house. None of them is with a remote switch, because I had not known we could get those. But sometimes one needs to put the fan on or off (depending on the weather) in the middle of the night. It is a pain to get up to do so, and it is also risky, because when one goes out of the mosquito net, mosquitoes go into it. Then they have a field day (or night?) until morning, unless one gets up, puts on the lights and kills them in the net. So we decided to put a remote switch on the fan in the bedroom. I asked in all the electrical stores near our house, and they all said it did not exist. I had given up hope, until I got an ad in my inbox. It was people who felt too lazy to get up and switch electrical appliances on or off. I promptly bought one. Unfortunately it had no instructions on its installation. I checked the net, and found a video on Youtube, It was for the same model as the one I had bought. But it did not explain how to do it clearly. The fellow would have done well if he had shown a circuit diagram. I consulted the electricians whose wives and daughters I had been treating all these years.They explained the principles to me. They even offered to do it for me, which I declined. I said I wanted to feel good by doing it myself. I thought it was a piece of cake to do it. Well, it was not.
I got home. The Youtube fellow had stressed that the first step was to switch off the main electric supply so that one would not get electrocuted. I did that. It was quite easy. Then I opened the board with all those sockets and switches. The trouble started there. It looked so much different from what they had described. Wires went everywhere. There was not much of a color code. I had to study the contents far longer than I study the inside of a patient's abdomen during a laparotomy. I was sweating, but could not switch on the fan because the electric current was switched off. Finally I worked out the connections, and worked out a plan, which I want to document here, so that anyone else who wants to do it himself/herself but has no training of doing so can do it. The principles of the procedure are as follows.
(For amateurs only)

1. The second one (the first one is switching off the current, remember?) is to draw a clear diagram of how the connections are. This is important because if what one does in there does not work out, one should be able to undo the damage and go back to the initial state.
2. The third one is to draw a diagram of how one wants the connections. I have shown the two diagrams above, 'A' being the starting position, and 'B' being the end position desired.
3. The fourth one is to disconnect the wire ends that have to be disconnected.
4. The last one is to connect the ends as per one's circuit diagram, seal the joints with duct tape, put the lid back on the box, switch on the electric current and test your work.

(Note: it is better to have someone around who knows how to administer cardiopulmonary resuscitation and call the fire department in case things go horribly wrong. They probably won't if one follows all steps correctly. :-) Ah! Nothing happens if you switch off the mains before starting, and if you have a tripper for when you try out what you have done.)
The remote switch has two sets of wires coming out. One is for giving it electric supply from the mains, and complete the circuit by joining it to the neutral of the mains. The other set is for running appliances. I have shown only one such wire, but my device has three such wires, which means I can run three devices using that switch. The steps are as follows.

1. As shown in the diagram, one disconnects the wire between the switch of the fan and its regulator.
2. The wire for supplying electric current to the remote switch is connected to the empty place on the switch.
3. The wire of the remote switch for connecting to a device (a fan in our case) is connected to the now free end of the input wire of the regulator.
4. The wire of the remote switch for connecting to neutral is connected to the neutral wire of the mains.
5. I am not clear about the function of the antenna (marked as A in diagram 'B'). I suggest leaving it out where the remote control can sense it, in case that is its purpose.

It works like a charm.

Door Stopper

A door stopper prevents a door from closing. Our operation theaters have automatic door closers, which keep the doors closed when no one is passing through. It makes moving about inconvenient to theater personnel, who open a door fully and tie its handle with a string to something unyielding on or near the wall. This is a door stopper of sorts. It causes stretching of the spring in the door closer permanently after a while, so that it does not function ever again. They do not know what their actions do, and they don't care when they are told what their actions do. They want the door open and they get the door open and keep it open. Period.
On the other hand, we need door stoppers in the house so that the doors remain open and don't bang closed with strong winds, especially in the monsoon. We have wooden stoppers fitted to the door frames, which wedge in the angle between the frame and the open door. Unfortunately their hinges become loose and it is a hassle to get a carpenter to repair them - carpenters want to be hired for the whole day, not just for a small job. I wonder if any doctors do that to anyone, especially to carpenters - get hired for the whole day, not just for removal of an appendix in half an hour or a toenail in five minutes. Anyway, getting a carpenter not being an option, I had to fix a door stopper somehow. Initially I tried putting folded pieces of thick card between the door and the floor. It worked until the card-wedge got thinner due to continued use, or the maid servant swept it away into trash. Then I had an idea. I use a lot of ballpoint pens to write patients' notes, do office work etc. The pens are use-and-throw type. I saved a cap of one such pen, heated its open end over a gas flame, and compressed it with pliers. Thus it turned into a wedge. It stayed put between the door and the floor when wedged there. It did not get soggy when the maid servant cleaned and she was smart enough to know it was not trash, especially after we told her so. Now it functions as a good door stopper. The following picture shows it in a 3D form from two different angles (A and B).

I could make as many of them as the OT personnel want, but won't because I care for the automatic door closers in the OTs.

How To Repair A Tap

The most common serious problem with a tap is wearing out of the threads of the gland nut shown below. As a result, the gland does not push down the jumper and the washer over the distal part of the jumper firmly, but keeps rotating through 360 degrees. The washer does not make firm contact with its bed and shut off flow of water. Then water keeps leaking even when the tap is closed. The only solution plumbers offer to this problem is to replace the tap with a new one. That is what we always did all my parents' life and all my life too, until I decided to experiment with it.
The following 3D image of an old-fashioned, conventional tap shows the tap in a dismantled state, with the shield removed. I opened the irreparable (as diagnosed by the plumber) tap in our house, and removed the jumper with the washer mounted on it. Then I put another washer over the tip of the jumper, so that there were two washers, one below the other. That is shown in the second illustration.

Then I put the jumper-washers assembly back and reassembled the tap. Voila! The tap was fully functional. It has been quite a few days, and the tap is still working fine.
I have another solution to this problem too. It is to increase the height of the jumper. I could do it by fixing a rigid plastic tube of proper size (to be decided by experimenting, or by trial and error) over its upper end. Then the lower end of the jumper-washer assembly will be lower than usual, and the washer would shut off the flow of water before the turns of the gland nut reach the worn out part.
I wish I had thought of all this years ago. Then we would not have had to throw away perfectly reparable taps and buy new ones which had no guarantee of lasting long.

Lights Please

I have been used to working in the OT with less than optimum illumination. We had ancient OT lights, which had been repaired by the local electrical engineer so many times, that none of them had any of the original parts left, except the base plates and suspending rods. Sometimes they would blink off. Sometimes they would show some spark followed by smoke and then go off. Sometimes they would blink off and on when the domes were moved to change the position of the spot. When I became head of the department, I decided I had had enough. I processed double-dome lights, one for each operation table. It took me five years of struggle to complete the process, which was like a hurdles race. Finally we got the new lights. Unfortunately, I had to be happy with only one dome per table in one OT, because we were forced to keep two OT tables in one OT (where there was not enough space to put two lights) and keep the other OT vacant, to be made into a modular OT. But that is another story. The lights were good, and even one dome was sufficient for each table. Sometimes we added another small spot light to it when we were performing vaginal surgery.
I had to wash up to help in a vaginal operation today. When I started operating, I thought the light was less. They already had the small spot light on, and still the illumination was less. I asked for more light twice, and the attendant juggled the inclination of the dome to try and improve the illumination. It did not work.
"Is something wrong with my vision?" I said. "I hear the vision becomes dark with retinal detachment."
No one assured me I did no have any such condition. But no one agreed that the light was less too. I think they were so tired that they just wanted the case to get over so that they could wash out. I finished the difficult part and handed the case back to the original operating surgeon. When I washed out, I happened to wander to the wall switch and look at it. It looked like this.

"Hey, look at this" I said. "Someone has reduced the illumination of dome 2 to half." The indicator for dome 1 showed full illumination, which was for the other table. Only half the LEDs for dome 2 were lit.
They looked. No one offered any explanation or agreed that he/she had done it. We increased the illumination to full, and suddenly the operative field glowed with light.
"Perhaps you had a fight with the attendant sometime" I said to the operating surgeon, "who reduced the light to get even?"
There was no answer.

Repairing a Sterilizer

My wife has a boiler type of sterilizer in her clinic, that she uses to sterilize metallic instruments before storing them. She gets them autoclaved before they are to be used. She could primarily autoclave them, but she does not use them often, and the effect of autoclaving does not last for more than 24 hours. She does not like to just get them washed and dried after use, because they can still harbor bacteria and viruses.
The sterilizer started leaking water one day. The electrician could not repair it, and advised us to get it sent to the manufacturer.
"I think the rubber washer has gone" she declared. "Can you fix it?"
"I would love to" I said. She knew I loved to fix things like this. So she smiled and handed it over.

The sterilizer had an electric resistance element inside it, which came out of one side through a circular opening. A disc shaped rubber washer was fitted between the element and the inside wall of the sterilizer, to prevent leakage and also for electric insulation. It had stiffened and broken into pieces from repeated heating and cooling. We removed it. But we could not find a suitable washer anywhere. Finally an electrical shop offered us a washer. It was thinner than the original one.
"What if I put two of these?" I asked the shopkeeper. "The combined thickness of the two should be equal to the original one."
"Yes. You should fit two washers" he agreed and sold me two washers. Good salesmanship, I can see it retrospectively. I fitted two washers, one above the other, between the element and inside of the sterilizer. My wife filled it with water and it leaked promptly. I started thinking about what had not worked properly. Finally I had an idea. 'Maybe water leaks between the two washers, and if I use only one washer, it won't leak.' So I removed one washer and refitted the element. My wife tried it, and it did not leak a single drop of water.
"So the thickness of the washer had nothing to do with it" I said. "One learns as one works, what?"
"Yes" she said, happy that I kept learning and solving her problems. :-)

Dynamic Handling of Tocodynamometer

The well being of the baby during labor is assessed by recording the fetal heart rate and maternal uterine contractions during labor. The uterine contractions are recorded using a simple gadget called as a tocodynamometer, which is shown below.

The transducer used for this is strapped to the patient's abdomen over the upper part of the uterus. It has a disk projecting out from the middle of the maternal surface. There is a spring under the disk. When the uterus contracts, it rises forwards and compresses the spring. This mechanical energy is converted into an electrical signal, which is carried through a cable to the recorder, which writes on a moving strip of paper. The fetal heart rate is recorded on the same paper using another device.
The job of fetal heart rate monitoring is usually done by the Resident Doctors. Actually all transducers have to be strapped to the patient's abdomen, so that they do not fall down. They break if they fall down. Another reason for strapping the tocodynamometer is that the spring has to be compressed to a fixed level when the uterus is relaxed, and only then it can give an idea about the force and duration of the uterine contractions.
Once we were taking a round of the labor ward. I found a patient connected to a monitor there. The patient was holding the tocodynamometer with her hand, while the heart rate transducer was strapped with a belt. The Resident Doctor who was doing the monitoring was with another patient.
"May I ask why the transducer is not strapped to the patient's abdomen?" I asked.
She promptly replaced the patient's hand with her own. "The other transducer is strapped" she said.
I took the transducer from her and asked her if it was recording uterine contractions well. She said it was. I held the disk over the spring facing away from her and pressed it. The record immediately showed a powerful contraction which just would not go away, because I kept pressing on the disk.
"What a strong and long uterine contraction!" I said.
She looked suspiciously at my hand. "You are pressing on the disk" she said accusingly.
"Exactly" I said. "The same thing can happen when the patient gets a painful uterine contraction, or just holds the transducer tightly. She might let the grip become loose, which will result in loss of recording of the contraction. If you are holding it and someone calls you, you turn around and the hand presses the transducer on the patient's abdomen. That produces a false record of a contraction." I demonstrated what I meant. It did what I had just said it would do.
"Now I hope you understand why both the transducers should be strapped to the patient's abdomen."
I hope she understood it. I am hoping against hope she will do what I told her to do - after all there are many reasons for not following standard operating procedures.

Oil Can Engineering

Edible oil is available in plastic cans. We buy it in cans of capacity of 5 L. We transfer a small quantity at a time from that can to a small container, and replenish its contents as required. A problem with this system is that the oil pours out in an unruly manner. That makes the process messy, and wastes a bit of the oil too.
"See if you can fix this problem" my wife told me. I was home because I was on Diwali vacation. I was glad to have something to do. I had known the problem, having carried out the procedure myself once. I thought about it a bit, and realized that the oil poured out of the can creating a sort of empty space inside the can. The can had to suck in air before it could pour out more oil. That produced a very turbulent flow, waxing and waning, and spilling out in different directions with time. There had to be an inlet for air, so that the oil would pour out in a smooth flow. I burned two small holes in the hollow handle of the can using a heated nail. The fixed oil can looked like this (arrow on the holes).

Then I tilted the mouth of the can over the small container. The oil poured out in an even stream, spilling not one drop outside the container. After filling the small container, I put a piece of adhesive tape over the holes, so that air and bacteria would not enter it.
"That was wonderful" my wife said with a broad smile. "How did you think of it?"
"I must have remembered laws flows of fluids from school or college physics" I said. For those who have not been able to visualize what I have described, I have put the illustration below. The left part shows the unruly spill, and the right part shows the smooth flow after fixing the oil can.

Fixing A Key Ring

One of my acquaintances wanted to wear the key ring on a chain or a tape around the neck while working in the OT. That became essential when the pockets of the OT dress started having holes or the stitch at their bottom started coming off. The key to the OT locker would fall out of the pocket causing no end of a bother. He procured a tape of the type used to wear identity cards around the neck. He put the key ring through the loop of the tape. Unfortunately, the spiral of the key ring rotated in the reverse direction and the ring came off the tape and fell off. Needing this thing fixed and knowing my happiness at fixing things, he approached me. It would have been easy to get the engineers to weld the two ends of the ring together. But it would have been sort of irreversible. The heat of the welding would have burnt the tape too. I fixed it as follows.

I took a piece of plastic tubing of an intravenous infusion set. I heated the ends of the spiral on a flame. Then I threaded one end of the piece on one end of the spiral ring, and the other end on the other end, before the ends cooled down. This produced a continuity of the two ends such that if the ring rotated in the reverse direction, the loop of the tape would just move from one end of the spiral on to the other end, but never come off. I heated the ends of a set of pliers and squeezed the tubing over the spiral ends so that the plastic melted a little and stuck to the spiral. The plastic tubing was transparent, so that the key ring did not look odd. Who is going to notice it in the OT around the neck of a male anyway?

(It took me ten minutes to think of this idea, another ten minutes to assemble the components and tools and do it,  and one hour to prepare its 3D model on my computer.)

Modified Air-Conditioing Vents

I will say my training at my hospital helps me survive in places far from my hospital. I was in New Delhi for a conference that involved the health ministry, UNICEF and others. It was at a famous 4 star hotel. We had to stay at that hotel for convenience. It was a good hotel and the arrangement of the conference was superb. The trouble started when I reached my room after the day's work. I planned to go to bed but it was so cold despite the summer heat of New Delhi, that sleep would be impossible. There was central air-conditioning, and it was almost as good as that in our emergency OT soon after installation. I shivered continuously in the hotel room just like in our OT. I looked for the remote control to adjust the temperature and found there was none, just as in our OT. I called reception and asked for increasing the temperature a bit.
"Sir, I am afraid that is not possible. It is centrally operated unit, and the thermostat is set for the whole hotel" the fellow manning the desk said.
I reviewed the situation again. There were four bed sheets and two blankets. I could be warm under the lot. But the problem was that my face and ears would freeze after I went to sleep, because I could not cover my face with the blankets. If I did, I would be a stiff (meaning dead as in American comics) from asphyxia instead of being just stiff with cold. It was at this was the pointthat my training at my hospital helped.

I climbed a chair to reach the vents of the air-conditioning from which the ice cold air was being pumped right onto the bed. I fixed a stiff card (don't expect me to say where I found the card - the hotel management might get offended by the answer) over the vents as shown above. Diagram A is the outside view, B is as it would be seen from the inside of the vents. This covering of the vents is used extensively in the OTs when it gets too cold. After a few months, the air-handling unit loses its force and the covers become unnecessary. I don't know if it is OK to do so, but it works in OTs and it worked in the hotel room too. After a good night's sleep, I removed the card, restored it to its initial shape and glory (that should please the hotel management in case they have figured out where I got the card) and went about my business.

Funky Knife Handle

Good things are said not to last forever. Well, we had a good knife. One morning its handle came off the blade. We could not use it any more because we dared not cut anything holding only the blade. We could not embed the blade into the handle, because it is a machine process and we did not have any machine that could do it. I could throw it away and buy another, but was reluctant to throw away a perfectly good blade. Then being a gynecologist helped. I had a sturdy plastic applicator that came with a tube of vaginal antifungal cream tube. I had given the tube to some patient while the applicator had remained. I removed its plunger. Then I held one end of the knife with pliers and embedded its other end into the tube. I was lucky that it was a tight fit.

It works wonderfully. I think I can apply the same principle to fitting scalpel blades when the Bard Parker handle is not available due to any reason. I will need a smaller diameter stiff plastic tube though.