Power in use indicator please ?

I donno what time delay you desire but one of the beauties of mosfets is that the gate requires no current (in the picoamp range) so you can use high value resistors to good effect.

It is pretty much the same deal with the input to the comparators of a

What I'm saying is that if you want really long time delays, the mosfet and 555 face the same limitations, and you'd still resort to counters etc. to increase the delay.

If your concern was the threshold of the 555 is 2/3 VCC and with a 15V supply that's 10V. That would be an argument favoring a 555 IMO. There are work-arounds for the mosfet but I might opt for a 555 then too.

For instance if a hibernate command is 8 minutes (for the sake of argument) and you're allowed to count 8 bits that's 17 hours, if you want to multiply that by another 8 bits that's 90 days, and you can keep doing that....

Ya, he said pumping water from the lake, I assume he uses it to water the lawn, so the pump might run an hour or more. Even with a 1 Meg resistor, that's a big cap. would help to drop the Vcc to 5V.

At one time I had button near my thermostat with an RC circuit that turned on my air conditioner for a switchable 2 or 3 minutes. Just enough to get comfortable. After the time out, it reverted back to the thermostat. It used a a latch type relay.

I reduced the Voltage to 5V and added an In Use Indicator.

The 5v option and diagram is interesting. The problem I had when I built th e circuit , built on me removing the secondary from adapter was that I coul d only get maybe 3 loops of 14 gauge household wire looped in the space of the removed coil of secondary wire. Is there a size of ac adapter that woul d be best to try to get 5v or more out of with as few coils of 14 gauge loo ped in transformer. Eg. In my box of old ac adapters 5v, 12v, 24v etc. Woul d a higher wall watt give out better output? My original unit has worked fo r maybe 15 years. Looking to replace. Btw. It pumps water for house, kitche n etc. toilet. Never thought about lawn or washing car but, where I live no body worries too much about this. There are other solution's that people ha ve suggested they are helpful and appreciate the options and efforts.

lower wattage adaptors will have more turns on the (original) primary but room for fewer turns in the window. I think they will all give approximately the same output, voltage with the turns windows backed. but larger transformers will be able to run larger loads.

So I suspect the timing can be shorter, Your just topping off the tank. So Maybe 5 or 6 minutes, but even if it spring a leak and ran 10 minutes, I don't think that would hurt the pump.

I have no clue about the turns required. I have a bunch of MicroWave transformers and cores, I would just wind it until it works. I might start with a MW transformer and remove the HV winding and the shunt pieces and wind 3 turns and see if I need to take some off or put some on. A MW transformer has plenty of room. But I also understand working with a smaller core.

Mikek

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My pump is a dual capacitor type. A start cap with a timed disconnect, a nd a run capacitor. I bought some clamp type current transformers for it. I also added a few digital meters to be able to tell if it is running proper ly. For remote monitoring, I could add a transmitter, or fiber optic cable when I replace the underground power lines. I could monitor it from the hou se, if the same lines didn't power the laundry building and some outdoor ou tlets.

Here is what I bought:

Should work. Practically, when using high turns ratio transformers, it isn't a bad idea to put some kind of voltage snubber just in case a spike comes along the primary side.

I had a nearby or direct lightening strike that took out the modem, TV, VOIP, all the low voltage LED grounds lighting, one ground fault interrupter, and tripped two circuit breakers in the panel.

Back when I was tinkering with my water heater project, I got one of those small side-by-side transformers. Square core with the primary on one side secondary on the other. Better than the E-I cores IMO.

Then I wired a 12 position rotary switch so it would switch in 470 ohm resistors as a load then measured the current and voltage. It went from zero ohms, 470, 940,... up to 4.7K and open circuit, measuring voltage and current at each step. I found the maximum power transfer to be ~2K ohms, with a pretty bell curve. That is where the load dissipated the most energy. At either extreme of the load power was significantly less - something to keep in mind.

The circuit is still on my water heater and has been working for >10 years now. I have a flashing LED that flashes faster as current increases (like when one heating element is on or both) and a piezo buzzer that comes on when power is applied (I put a switch on the water heater to save money) and again when the current drops to zero (buzzer sounds for as long as a cap can keep it working)

My water heater pulls ~20 amps 240 V and when I breadboarded the circuit, I was using my 40 watt soldering iron as a dummy load. I think the water heater only needed two turns of wire. It's been too long ago to remember it all accurately.

We had a hurricane a couple years ago, either lightning or power surges, damaged three items in my home. All were in my computer area. My computer HD got corrupted, my portable radio plugged into a wallwart and my fluorescent table lamp. The modem, router and printers were fine. Oh, and about $90k of damages to the home.

I live on he East coast and evacuate about once a year for a hurricane. Rising sea levels are a concern too, we already lost the oak trees and now the pines are starting to go.

I figure with a pump (1/2 HP 120V) there has to be plenty of inductive kick as it switches on and off That alone should translate to serious spikes in the secondary of a current transformer.

Inductive kickback produces voltage spikes, not current spikes. A proper current transformer isolates against the voltage spike. So, no problem.

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Huh, I didn't know that. Since this is an indicator going back to the house it's also got ~120 AC riding on the wires feeding the led.

George H.

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Hmm, how about putting a 5 Volt wall wart across the pump. And running an LED or other indicator off the 5V. (or could be whatever wall wart voltage you have laying around...)

George H.

Most water heaters only have one element on at a time. Is this a special water heater ?

I don't think it's anything special. There are two thermostats and two independently controlled heaters. If I'm gone for the weekend and power is off, it appears when I power it back up, that both elements are on for a time.

I think if the upper heater is thermostat energized, that thermostat prevents current to the lower thermostat and heater. This should about cover it.

That'd work if you're prepared to install a second cable back to the house, the current monitor OTOH can be installed at the house end of the cable.

Yes pretty much anything has to be installed at the power , house side. It always amazes me how a simple question , Generates a huge volume of conversation. A friend one said to me electronics is a bit of a black art.