“There are two novels that can change a bookish fourteen-year old’s life: The Lord of the Rings and Atlas Shrugged. One is a childish fantasy that often engenders a lifelong obsession with its unbelievable heroes, leading to an emotionally stunted, socially crippled adulthood, unable to deal with the real world. The other, of course, involves orcs."
This is a discussion forum for intellectual curiosity operated from the investment exhaust of a capital market participant. A recent, adjacent analogy is Jeff Lawson taking his Twilio winnings to buy and operate The Onion. The economic mechanizations are usually underpinnings to something more valuable. HN would still be valuable if YC closed up shop tomorrow (and I personally argue, of greater value than the accelerator; value is subjective of course, so opinions will differ on this). Stay curious.
> How do I monitor whether the contacts are closed or open? I assume with a GPIO pin, but I’ve never been able to google this question and find anything of use.
Without making assumptions about the microcontroller used, attach ground to one of the contacts, then attach a GPIO pin, the other contact, a 10k resistor (or 100k), and VCC together in series. The microcontroller should periodically read the GPIO pin. If it reads high, the contact is open and the alarm is not sounding; if it reads low then the contact is closed and the alarm is sounding.
The GPIO / contact / resistor / VCC arrangement acts to pull up that side of the circuit to the high logic level, and the resistor will limit the current that flows whenever the contacts close. If your microcontroller has an internal pull-up configuration for GPIO pins, you may be able to attach the pin directly to the contact without the extra hardware. (Conversely, if it has a pull-down configuration you can reverse things, attach VCC to the contact and the GPIO directly to the other. Read your microcontroller's documentation for available features and any current limitations.)
Reminder: good estimates place the number of people in the cryptocoin system in the 100,000s. BTC can support c. 7 transactions/sec. Ethereum c. 20.
This is a scam. It's a self-organizing pyramid scheme. There is no "there" there -- the vitamins really arent a cure for cancer, and your friend telling you to buy a warehouse full is part of a cult of pushers who are desperate that their warehouses of vitamin pills (ie., tokens) doesn't become entirely unsellable.
All the numbers reported by the cryptocoin system are made up: these are manipulated markets with almost no buyers. "Market cap"s are inventions. The amount of actual liquidity in the system is tiny: people are looking for the exists. These exits are mugs called "hodlers", ideally, You, who'll buy their vitamins from them.
Usually, HN comments ought be somewhat more sober -- but I think this is now out of line. Sobriety in this matter is enabling a system of exploitation which should not be entertained by decent people.
The Depository Trust & Clearing Corporation settles most listed securities transactions in America; in 2011, it did $1.7 quadrillion [1]. You've never heard of it unless you're a professional trader, but it's actually quite fascinating to read up on.
Trading looks instantaneous. But settlement takes a few days. In between are a series of credit agreements. From your broker to you. From the clearinghouse to the brokers. DTCC is the clearinghouse. Robinhood is the broker.
There are rules and contracts between DTCC and its members, including Robinhood [2]. Those contracts ensure that when you buy shares through your broker from a Robinhood customer, if Robinhood falls down two days later, there is collateral sufficient to make you whole. Those collateral requirements change in reference to, amongst other things, the volatility of the security. (If a broker falls down, the clearinghouse liquidates their collateral and makes their counterparty whole. More volatility means more chance the collateral will be insufficient.)
In this case, collateral requirements on GME went up. Because of its volatility. So while before Robinhood had to pony up collateral for a few shares of GME for every hundred it traded, it now had to, at close of business, pony up one hundred shares' worth of collateral for every hundred it traded. That creates a cash crunch. One that exacerbates itself with every additional trade in the security. If Robinhood fails to satisfy those collateral calls, they go out of business overnight. Into receivership. Done.
Most brokers have policies for these situations. Higher brokerage fees for securities on a schedule. Not making shares and cash from trades available until the trade settles, sort of like what banks do for large cheques. But I don't know if Robinhood is able to do that quickly. So instead they pulled the plug.
https://www.goodreads.com/quotes/366635-there-are-two-novels...