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This is one of the scariest capacitors I've ever removed from a circuit.  Even though the unit had not been used for a long time, I still treated it as potentially holding a charge and applied suitable handling precautions, including applying a 1M resistor across it one lead at a time.

https://youtu.be/gORJQVoH1ec

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Inside a Zoll defibrillator - with SCARY capacitor

This is probably the SCARIEST capacitor I've ever removed from a circuit. It's entire purpose in life is to stop people's hearts - but for a good reason. The days of defibrillators being big scary hospital machines are long in the past. These days they are a very affordable piece of first aid equipment that should be in every public place and workshop. The science behind modern units is stunning. When the pads are applied to the chest of someone in a suspected state of ventricular fibrillation (heart out of sync), the unit will monitor the heart's electrical signal and decide if it is good or if there is an issue that needs a resync pulse. If the pulse is needed it calculates the best timing and strength of pulse to achieve the highest success in bringing the heart back into sync. During the whole event the unit talks you through every part of the process, and even applying the pads is made easy by the clear instructions printed on them. It's important to note that the unit will not "shock" a heart in what it regards as a safe condition. It only applies a resynchronisation pulse if it detects that the heart is out of sync and that death is imminent. Sadly it can't do anything if the heart is flatlining, as that is a tough task even for trained paramedics, that may involve injection of drugs to directly stimulate the heart. It is MASSIVELY important that a defibrillator is applied as soon as possible in the event of an incident occurring, as the chance of survival reduces dramatically with time. If in any doubt about whether there is a heart issue then apply the unit, as it can help make a medical diagnosis. Paramedics will often keep the original electrodes in place with an adaptor to suit their own equipment. The cost of a replacement set of electrode pads is insignificant compared to the loss of a life. Although originally designed to save the lives of American utility workers (who usually work on live high voltage equipment), it's unfortunate that many do not have these in their utility trucks yet, despite the fact that their cost is insignificant compared to many of the other specialist tools they use. The Zoll units (not a sponsor) are one of the most affordable available, as they use standard batteries and the pads have much longer storage life (up to five years) than many other brands. Most modern defibrillator units keep a record of every event they are involved in for future refinement of software and functionality. I do recommend sharing the logged data with the manufacturer to allow them to improve the functionality of their units. The circuitry in these units is very impressive, since it can use the same pads to monitor very low voltage biological signals and also apply high voltage and high current pulses. If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- https://www.bigclive.com/coffee.htm This also keeps the channel independent of YouTube's algorithm quirks, allowing it to be a bit more dangerous and naughty. #ElectronicsCreators

Comments

Mike Page

To get it to "bang" you need a thing called a "patient simulator" set to VT or VF. And a 25-125R load to soak up the electrons!

Gordo

Years ago a friend gave me a big box of defibrillator parts when his work (a defibrillator factory in Bangor, NI) were taken over by an American corporation and everything went into a skip. Among the parts were some large vacuum relays - I can imagine what those were used for..

Gordo

Btw, the Google translate app on my phone can successfully translate the spoken prompts into English..