Wants to find the voltage drop in the plug using basic stamp

Sandhuamarinder

Hello Everyone

I need help i wants to find the voltage drop in the plug which supply 110 V. How i can find this out. I dont wants to buy multimeter i wants to installs LED which shows that voltage did dropped and wants to see on LCD that at what time did it dropped something like that would be help ful i really need help no funds to buy the multimeter.

So biggest issue trying to figure out 110 voltage drop with stamp.

Thanks

PJAllen

• Get a neon lamp assembly and connect that to the "110".
• Couple the lamp to a CdS-photocell (LDR). [In other words, put that in an enclosure so that the only light on the photocell is from the neon lamp.]
• Use RCTIME on the Stamp to monitor the status of the photocell. [There are examples in PBASIC Help.] When the lamp is on then the photocell will have a low resistance.

Sandhuamarinder

Thanks for the reply great idea. But doesn't look like it is going to be that accurate depending on the sensor and depending on the inclosure since voltage does not drop that much but water leaks from my fridge. Ah. So cause of that is that there is humidity is the place i think. So now i need to check for the humidity in the place i think. Since voltage measurement idea looks like a fail.

V-man

Sandhuamarinder wrote: »

Hello Everyone

I need help i wants to find the voltage drop in the plug which supply 110 V. How i can find this out. I dont wants to buy multimeter i wants to installs LED which shows that voltage did dropped and wants to see on LCD that at what time did it dropped something like that would be help ful i really need help no funds to buy the multimeter.

So biggest issue trying to figure out 110 voltage drop with stamp.

Thanks

Hi Sandhuamarinder,

Multi-meters are pretty cheap, check out Radio Shack.

Otherwise you'll need to build a circuit that converts the110VAC to a DC level the Stamp can handle without letting all the internal smoke out!! Here are some thoughts: Take the 110VAC and connect to a Diode with the Cathode connected to one AC line, connect the other AC line to ground. Connect the anode of the diode to the positive side of a electrolytic capacitor, probably around 100uF would work (be sure the cap is rated for at least 200 volts). Connect the negative side of the capacitor to ground. Connect two resistors in series from the positive side of the capacitor to ground. The resistor connected to the positive side of the capacitor should be about 100K ohm. the second resistor should be about 2K ohm. That should give you a DC voltage of approximately 4 volts across the 2K resistor. Then you could use an AD converter to measure the voltage across the 2K resistor. Sample the value continuously at some period log the results and you should be able to see if there are any voltage drops going on. I know this is a bit complicated but it's the best I can give you based on the initial description of the problem you're trying to solve.
Good luck

IMPORTANT!!!

The circuit I described is a real poor-mans version of a half wave rectifier. I wouldn't use it in a real project, there are better designs, such as one using a full wave rectifier. I was only trying to point out a posible method to get the poster "Sandhuamarinder" pointed in the the right direction.

rwgast_logicdesign

Im curious what about the neutral line? Does it just get capped off? Does the neutral line not being use have something to do with the diode blocking the negative waves? In home appliances youll see the ground ditched I.E a two prong, but never the neautral since it acts as the current return path in the AC system.

V-man

Good question. The 110VAC from the wall usually has three wires; white=neutral, black=hot, and green is ground. The cathode of the diode would connect to the hot wire (black) then the anode of the diode connects to the positive side of the capacitor. The negative side of the capacitor connects to the neutral (white) wire and also becomes "Ground" for the DC circuit. However since this is alternating current the hot and neutral wires could be swapped. The diode is actually converting the AC to a DC current and the order of the AC wires won't matter. In the DC portion of the circuit the positive voltage is on the positive terminal of the capacitor and ground is on the negative terminal. The actual DC voltage on a typical 110VAC is approximately 160 to 170 volts DC (which is why a 200 volt capacitor should be used). The actual DC voltage depends a lot on how much load is on the DC circuit and the value of the capacitor.

Does that help or answer your question?

rwgast_logicdesign

wow i didnt know ac would convert to a higer dc i woulda guest elemenating the negative would supply half the dc power...

i only asked cuz ur original post only mentioned ground not neautral wouldnt wanna wire mains incorectly... 120vac isnt to much but still wouldnt wanna blow somethin up..

V-man

IMPORTANT!!!

The circuit I described is a real poormans version of a half wave rectifier. I wouldn't use it in a real project, there are better designs, such as one using a full wave rectifier. I was only trying to point out a posible method to get the poster "Sandhuamarinder" pointed in the the right direction.

V-man

rwgast_logicdesign wrote: »

wow i didnt know ac would convert to a higer dc i woulda guest elemenating the negative would supply half the dc power...

i only asked cuz ur original post only mentioned ground not neautral wouldnt wanna wire mains incorectly... 120vac isnt to much but still wouldnt wanna blow somethin up..

Right, AC voltages are indicated in RMS values. When a circuit is rectified, the "Peak" AC voltage is stored in the capacitor. To find the AC PEAK voltage just multiply the AC RMS voltage by 1.414.