Do It Yourself: 240v from two 120v sources

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TonyWilliams

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New thread for this topic:

From Phil "Ingineer":

"Just add two 120v coil SPST relays to your box and then there is no safety question.

You never know if someone's child might happen upon one of your two cables and pull it out and touch it with bare feet, or touch it and something grounded. If you will not be there 100% of the time guarding it, it's not safe.

In my home-made version I included the 2 relays, total additional cost was under $10. I didn't bother with a meter, but I added a super-bright blue LED and a buzzer that sounds for a few seconds once it "sees" 240v, that way you can easily determine if you've found the right outlets even if you can't see the unit. I included 8' of cord on the two cables, and in most all cases I can find 2 circuits within 16' of each other and still have the cables not take up a lot of space."
 
Here's my full original post that is in reference to people building their own homebrew "Quick220" device without adequate safety. See my post below for a schematic.

Ingineer said:
Just add two 120v coil SPST relays to your box and then there is no safety question.

You never know if someone's child might happen upon one of your two cables and pull it out and touch it with bare feet, or touch it and something grounded. If you will not be there 100% of the time guarding it, it's not safe.

In my home-made version I included the 2 relays, total additional cost was under $10. I didn't bother with a meter, but I added a super-bright blue LED and a buzzer that sounds for a few seconds once it "sees" 240v, that way you can easily determine if you've found the right outlets even if you can't see the unit. I included 8' of cord on the two cables, and in most all cases I can find 2 circuits within 16' of each other and still have the cables not take up a lot of space.

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-Phil
 
Schematic please, primarily for what you used for the LED and noise maker circuit... The other part is easy.

Ingineer said:
Just add two 120v coil SPST relays to your box and then there is no safety question.

In my home-made version I included the 2 relays, total additional cost was under $10. I didn't bother with a meter, but I added a super-bright blue LED and a buzzer that sounds for a few seconds once it "sees" 240v, that way you can easily determine if you've found the right outlets even if you can't see the unit.
 
Here's another post answering a question surely to be asked again in this thread:

Ingineer said:
Volusiano said:
Ever thought about building and selling your home version of the Quick220, Phil? I'm sure many on the forum would be interested in buying if you price it reasonably because the Quick220 seems way over priced.
I thought about it for about 1 second. It's labor intensive, so there would be no way to make money selling these in low quantity if you came in at a price point much below what Quick220 is selling theirs for.

I spent about 4 hours on it, so what's a "reasonable" price?!?

But in any event I simply don't have the time! This is one reason why we are closing for a few weeks. EVSE upgrades are consuming most of my time. Maybe during the shutdown I'll get caught up and actually have time to do things like draw a schematic for everyone. As realtively simple as the EVSE upgrade is, each upgrade sold seems to generate 11 emails on average, so customer communications/support/logistics actually consumes WAY more time than bench work. I can imagine the "Quick240" having even more support issues!

Because it's electrically pretty simple, this is a great DIY project, but I'd like to stress that everyone considering building one definitely include the 2 relays. If someone were to die because you were too lazy to include them, how would you feel?

-Phil
 
Ingineer said:
As realtively simple as the EVSE upgrade is, each upgrade sold seems to generate 11 emails on average, so customer communications/support/logistics actually consumes WAY more time than bench work.

Phil, you should consider going to 1-900 customer support system.. your time is valuable and your web site easy to understand.
 
Herm said:
Ingineer said:
As realtively simple as the EVSE upgrade is, each upgrade sold seems to generate 11 emails on average, so customer communications/support/logistics actually consumes WAY more time than bench work.

Phil, you should consider going to 1-900 customer support system.. your time is valuable and your web site easy to understand.
Yeah, we actually had a number for EVSE upgrade, but had to turn it off! It would be a full-time job and then some just taking calls. I can now understand how all companies are off-shoring their phone banks! Sadly, I can't believe how many people simply don't bother to read, and these are supposedly people hip on technology, or at least hip enough to get a LEAF.

-Phil
 
Here's a quick schematic of a basic safe unit: (Update: There is a more complex version with the audible indicator here.)

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The area in the shaded box is optional if you'd like to hook up an LED. You can also use any pilot lamp rated for 240v operation.

I recommend heavy-duty relays such as this:



-Phil
 
Ingineer said:
Here's a quick schematic of a basic safe unit. The area in the shaded box is optional if you'd like to hook up an LED. You can also use any pilot lamp rated for 240v operation.

pic


-Phil

Nice as hell, thanks!
 
mogur said:
What did you use for the buzzer?

Thanks!

Ingineer said:
Here's a quick schematic of a basic safe unit:
I don't have a schematic drawn for that feature. Basically the same power supply arrangement as shown for the LED, but an added piezo buzzer driven by a 555 timer configured as a one shot. It runs a few seconds when powered up on 240v, then goes silent. This way you know instantly when you've found the right 2 outlets without having to look at the LED. It also doubles as a power restored alarm in the event the power goes out and comes back on. =)

Update: See post below for schematic with buzzer feature.

-Phil
 
Now, it'd be great if somebody who will try to build this device can document where they buy their parts from so that we can just follow their footsteps instead of trying to hunt all over the place for parts. I understand the schematic and I think I can build from it, but I'm really not familiar with where to go to get parts.

Another option is if somebody wants to assemble all the parts and sell them out as a DIY kit for a profit. That way the labor for the assembly is on the buyer.
 
Ok, I added the Buzzer:

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Once connected to 240v, the Blue LED will light, and the buzzer will sound for about 3 seconds then it will silence. If you wish to change the time the buzzer stays on, simply change the value of C4. The value in microfarads roughly equals the time in seconds the buzzer will sound. All the capacitors in the timer circuit should be rated for 25v. Zener Diode ZD1 is 12v @ 1w, and BUZ1 needs to be a low-power 12v Piezo buzzer. The one I used is a Projects Unlimited PI-256K.

There is also a toggle switch (S1) that lets you select between 120v and 240v output. If you don't want it, simply jumper connections 1 and 2 together and don't use 3. If you do add the switch, it must be rated for your load, I recommend at least 25A.

For safety, It's very important to use a 10ohm 1watt flameproof or fusible resistor for R1 and that C1 be .22uF and a minimum of 300 volts. (you can go higher on capacitor voltage, but never lower!)

I do not recommend anyone attempt fabrication of this project unless they are qualified to work on electronics and high voltages. All parts in the circuit are connected to potentially lethal line voltages!

-Phil
 
Can someone elaborate on why you'd want the 120v switch? I must be missing something. Seems to me if you want 120v, just don't use this device at all... ;)
 
OK, my trip to the junk boxes resulted in some components that I used to build a slightly different version. The relay logic and wiring is the same as the schematic (I didn't use the 120/240 switch). However, I went with a different type of noise maker and light based on what I found.

I have an old 240VAC Sonalert that is a momentary type (it sounds for 5 second than goes off when power is applied) and I used that by wiring it directly across the 240 output through two 10 ohm 1 watt fusible resistors (one on each side of the Sonalert) for short protection.

Across the Sonalert I wired a 240 volt Neon cartridge indicator that I also had in parallel. Testing showed that the Sonalert wouldn't trigger on 120 but would on 240 so it was perfect for this. Likewise, the light is very dim on 120 but quite bright on 240.

Not as elegant but having all the parts available in the shop was a plus.
 
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