Can you just use a ubiquitous USB charger?
Most are at least 15W.
Or buy a fancy USB/120V Nema outlet...
home improvement turns into science fair projects?
- mediatechnology
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Re: home improvement turns into science fair projects?
My suspicion is that may be the problem, the charger ICs can have protection circuitry to prevent overcharging phone batteries.
desc wrote: Comprehensive Safety: CE/FCC certificated, Built-in safeguards protect your devices against excessive current, overheating, and overcharging. The wall charger will automatically stop charging when power is full, which can maximumly protect your device
I just looked again and one 15W unit I saw had 3 USB connectors. My suspicion it is 15W total not per.
Most are at least 15W.
I have another similar USB plug-in unit on order. I expect the USB outlets use the same switcher chip sets inside.Or buy a fancy USB/120V Nema outlet...
JR
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- mediatechnology
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Re: home improvement turns into science fair projects?
They're usually 15-20W total.
TI has a nice chipset for this function that supports fast charge (9V) and its various signalling methods.
TI has a nice chipset for this function that supports fast charge (9V) and its various signalling methods.
Re: home improvement turns into science fair projects?
After I get my replacement I may take this first one apart. If the replacement works fine, to see what went wrong with faulty unit.
If the replacement has similar cold temperature misbehavior to see what chip is used and try to find data sheet.
Alibaba sells the finished unit for $0.50 in large qty.
JR
If the replacement has similar cold temperature misbehavior to see what chip is used and try to find data sheet.
Alibaba sells the finished unit for $0.50 in large qty.
JR
Cancel the "cancel culture", do not support mob hatred.
- mediatechnology
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Re: home improvement turns into science fair projects?
So the material cost is what, 8 cents?
Re: home improvement turns into science fair projects?
My experience with large Chinese contract manufacturers is that they operate on pretty narrow margins. I would not be surprised about a BOM $0.25 to $0.35. I've seen some pretty skinny profit margins.
That's why they envy (and sometimes purchase) western brands making fat profit margins.
JR
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Re: home improvement turns into science fair projects?
Good progress integrating my blower (air mover) into my winter heating program.
For a couple years to save money I would only heat my bedroom at night using a time of day thermostat and resistance baseboard heaters. Now that I have a big dog (2T) heat pump heating/cooling my main room, I have experimented with sucking air from the main room to heat/cool my back bedroom.
I determined that the blower I bought (on sale) was way too high capacity for comfortable use. I figured out how to slow it down with capacitors in series. The instructions advise against using solid state speed controls.
I tried to use just the blower with my TOD thermostat, but it draws power through its load, and the blower was too light of a load. It requires a minimum 2A load. I had previously upgraded from a 1kW baseboard heater to 1.5kW when the 1kW was marginal output for cold winter nights. For chuckles I wired the 1kW in series with the 1.5kW, making a combined 500W load, drawing adequate current to power the TOD thermostat. Since the two baseboard heaters in series form a voltage divider, I can power the blower from the lower voltage or higher voltage fraction. On the higher voltage leg, I could hear a tone coming from the blower. The thermostat has 5 levels of heat output (likely PWM) that caused audible noise from the blower motor. On the lower voltage leg the noise was not audible and the blower still moved enough warm air from the main room to heat the back bedroom... This morning with overnight lows in the 30s the bedroom temp was well regulated and heat/blower alternately running (silently) at only 40% power...
I experimented with making a simple RC LPF using the junction of the two baseboard heaters as the R. I estimate about 5 ohms source impedance at that node. The only cap I had laying around that I felt comfortable using at that voltage was a 22uF, and it did not eliminate the noise (from high voltage leg). So one pole LPF -3dB at 1.4kHz does not quiet it down significantly.
Not a problem, blower runs silenty on lower voltage leg. I will need a different plan for cooling next summer, but no need to worry about that for several months.
JR
PS: This morning my laundry room greenhouse temperature was still well regulated to 50', while grow lights were locked up again, but I was able to reset them. Still waiting for replacement USB supply to suss that fault out. Not only did my pepper plants not freeze but I see two new bell peppers coming.
For a couple years to save money I would only heat my bedroom at night using a time of day thermostat and resistance baseboard heaters. Now that I have a big dog (2T) heat pump heating/cooling my main room, I have experimented with sucking air from the main room to heat/cool my back bedroom.
I determined that the blower I bought (on sale) was way too high capacity for comfortable use. I figured out how to slow it down with capacitors in series. The instructions advise against using solid state speed controls.
I tried to use just the blower with my TOD thermostat, but it draws power through its load, and the blower was too light of a load. It requires a minimum 2A load. I had previously upgraded from a 1kW baseboard heater to 1.5kW when the 1kW was marginal output for cold winter nights. For chuckles I wired the 1kW in series with the 1.5kW, making a combined 500W load, drawing adequate current to power the TOD thermostat. Since the two baseboard heaters in series form a voltage divider, I can power the blower from the lower voltage or higher voltage fraction. On the higher voltage leg, I could hear a tone coming from the blower. The thermostat has 5 levels of heat output (likely PWM) that caused audible noise from the blower motor. On the lower voltage leg the noise was not audible and the blower still moved enough warm air from the main room to heat the back bedroom... This morning with overnight lows in the 30s the bedroom temp was well regulated and heat/blower alternately running (silently) at only 40% power...
I experimented with making a simple RC LPF using the junction of the two baseboard heaters as the R. I estimate about 5 ohms source impedance at that node. The only cap I had laying around that I felt comfortable using at that voltage was a 22uF, and it did not eliminate the noise (from high voltage leg). So one pole LPF -3dB at 1.4kHz does not quiet it down significantly.
Not a problem, blower runs silenty on lower voltage leg. I will need a different plan for cooling next summer, but no need to worry about that for several months.
JR
PS: This morning my laundry room greenhouse temperature was still well regulated to 50', while grow lights were locked up again, but I was able to reset them. Still waiting for replacement USB supply to suss that fault out. Not only did my pepper plants not freeze but I see two new bell peppers coming.
Cancel the "cancel culture", do not support mob hatred.
Re: home improvement turns into science fair projects?
Just received my replacement USB charger so lets see if I had a personal problem with one faulty unit, or have a design problem.
I notice the package for this new unit says "for indoor use only" while my laundry room is technically indoors, just not heated.
It is in place and working, exposed to the laundry room temps (warmer than outside but still gets cold). Forecast for tonight predicts another night in the 30s so we'll see soon enough.
JR
I notice the package for this new unit says "for indoor use only" while my laundry room is technically indoors, just not heated.
It is in place and working, exposed to the laundry room temps (warmer than outside but still gets cold). Forecast for tonight predicts another night in the 30s so we'll see soon enough.
JR
Cancel the "cancel culture", do not support mob hatred.
- mediatechnology
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- Joined: Sat Aug 11, 2007 2:34 pm
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Re: home improvement turns into science fair projects?
Sometimes reads "Not for damp locations.""for indoor use only"
Good luck.
I bet it runs overnight this time.
Re: home improvement turns into science fair projects?
That is my hope, but we'll see.mediatechnology wrote: ↑Fri Nov 15, 2019 11:20 amSometimes reads "Not for damp locations.""for indoor use only"
Good luck.
I bet it runs overnight this time.
JR
Cancel the "cancel culture", do not support mob hatred.