Indeed, I was looking for a simpler and lower level protocol. Thanks for mentioning the network protocol anyway, because I have never heard of CoAP until now. It may come in handy in the future (or maybe for someone else reading the post).
I was ready to shit on this but I could definetely see some uses when there are a lot of through hole pins. I’d be a little worried about keeping the heat distribution even though.
I thought it might be useful to move the iron back and forth a little for long rows. Wouldn’t be perfectly even but would be better than concentrating heat in the center.
You can replace it with any resistor with the same resistance and power rating. It may be easier to solder a larger through hole resistor onto the pads. I think other posters have figured it out, but you can search for resistor code information to decode it yourself. You can buy resistors lots of places, RadioShack was the go to place but I think hardware stores sometimes have them. If you’re not in a rush I recommend ordering a kit with a few different kinds.
Find a latching relay. I built something similar where I had a battery powered circuit that needed to be on for a long time. This is different than making a latching relay from a normal relay. A latching type relay uses a pulse. You send a short pulse down the line and it flops over. The datasheet will tell you the pulse width.
The trick is to keep soldering tip always wet from solder and only clean it just before you solder. Second, always when done soldering and you cool down you soldering iron, melt fresh solder on the soldering tip before it cools down.
Hm, that’s an unusual issue! I don’t know off the top of my head, but I’ll ask a few questions that might help diagnose the problem.
What kind of soldering iron are you using? A soldering station, or a dollar store ‘firestarter’? Also the wattage? It should be printed on it somewhere.
What type of solder are you using? It’s electronics solder, right?
You’re not getting molten plastic on the soldering iron tip? That tends to ruin them pretty fast.
Can you show us the other side of the drive? Curious what make/model this is supposed to be. Best guess is that this is yet another attempt by a PC manufacturer to sell un-upgradeable units that need to be either replaced as a whole, services only by then, or had at with wire snips and a soldering iron.
I’d say it’s time to carefully cut out that tab (leaving the keys intact), and to start being more careful about what you buy.
Unless otherwise specified at certain loads, relay duty cycles are always 100%.
Most relay duty cycles are in relation to switching currents, not the coil operation. There is always a slight resistance between dissimilar contacts, and carrying current across the contacts creates heat, so they have a max rated current for continuous use. They can often exceed this, but only for short periods before needing a duty cycle cooldown.
When the relay switches high near-max currents, especially in DC, it generates a large arc across the contacts. This makes them heat up. This limits the actuation frequency because too many arcs at max/overcurrent will overheat the contacts and could cause them to fuse together.
But the coil itself is designed such that it will never overheat on it’s own just from the trigger voltage. Granted it’ll waste a lot of power to resistive heating that is undesirable if your goal is power efficiency, but it will be perfectly OK.
I’m a little new to the terminology, so to clarify, the switching current refers to the amperage across the terminals other than the coil, right? I’m definitely within those limits; I don’t expect to transfer more than ~1/8 of the maximum amperage.
Is there a rule of thumb for the minimum current I should allow across the coil? The only specification I see on the datasheet for coil amperage is that it was tested to failure at 100mA. I don’t think power consumption is too big of a deal with this use case, but resistive heating sounds like it could shorten component life (and even if it’s only a secondary consideration here, I’d still prefer to minimize waste).
the switching current refers to the amperage across the terminals other than the coil
Yes. “Switching current” is the load current being controlled across the main contacts. I figured you were well within specs, I was just clarifying what typically limits relay duty cycle other than the coil.
Is there a rule of thumb for the minimum current I should allow across the coil?
Stick to the rated coil voltage in the datasheet or below and you’ll be fine. They set the coil resistance to be within the safe current zone per V=IR at rated control voltage.
Many relays can reliably switch well underneath their rated control voltage depending on their design- there’s a lot of safety factor built in. I’ve had some 12v automotive relays switch successfully at around 5v (by accident, lol). Experiment a bit and you may be able to cut down on waste power
Just be aware that control voltage (coil) and rated switching voltage (load) is often different, since many relays use low control voltages to switch high voltage loads. Don’t confuse the two!
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