replacing Batteries for a Wall Wart

[dude]

Not really amp   related but I know someone here knows the answer:


Wife has three battery candles (each take three 1.5v AAA, have there own on/off switch). Batteries last only few days, want to use a wall wart. Do I wire them each in parallel skipping the batteries, using one 4.5 volt DC wall wart for all three?
 
I'll delete as soon as I get an answer, been searching all over, no luck. Pretty sure I got it right but not 100%.

[shooter]

each take three 1.5v AAA

are the batteries in series, or parallel?
guessing series since you have 4.5v wart, the "Bpack" should have 2 wires, snip them, put a diode, anode at the wart, cathode to Bpack + wire that feeds the lights, wire Bpack - that feeds the lights to wart -

[dude]

Yeah, series 1.5 x 3 = 4.5v each candle. Have three candle this way. The wall wart feed plug is cut so I can use polarity any way I want  Has switch for 3, 4.5, 6 and 9V. I'll use 4.5vdc out.

So cut the wires from the pack, leaves me with -, + on each. The wall wart is putting out 4.5vdc, why do I need a diode? Couldn't I just snip the packs out, run all the + wires to the + side of the wall wart and neg to neg. All in parallel? Why diode?

Wouldn't that give me 4.5vdc to each candle, as I already have dc from the power source, the wall wart.I

I assume yo uwere thinking the wall wart put out ac

[sluckey]

The diode is for reverse polarity protection. I assume your candles are actually LEDs. LED reverse voltage rating is typically 5V but it doesn't hurt to provide extra protection. If your candles are incandescent bulbs it doesn't matter.

[ac427v]

Last year our battery candles with incandescent bulbs got tossed--the batteries needed replacing every 3 days. We got Home Depot l.e.d. candles with built in timers and the batteries lasted all winter!!!
--Craig

[dude]

The diode is for reverse polarity protection. I assume your candles are actually LEDs. LED reverse voltage rating is typically 5V but it doesn't hurt to provide extra protection. If your candles are incandescent bulbs it doesn't matter.

Always learning, yeah LEDs kind of flicker, pretty neat, wife loves them. So the the diode stops the voltage that passes threw, if polarity gets reversed. The wall wart puts out 5.7vdc on the 4.5v setting, think that'll blow the LEDs?


Would I need half watt R, before the diode to lower to 4.5v?


Thanks Shooter, appreciate you're help.   

[sluckey]

You'll be fine. Hopefully! 

[PRR]

While old-school LEDs would stand a little reverse voltage if the current were limited, I'm told some new ones are pickier. If they "flicker", they have a chip, and chips generally HATE reverse voltage. (However I did once put in a 8080 CPU backward, it got HOT, I flipped it, and it ran for years.)

You know which end of the battery is +. You know which wire of the wart is +. Get it right.

[dude]

You know which end of the battery is +. You know which wire of the wart is +. Get it right.

My trusty meter tells me that, if no " - " shows on the screen the red lead is +.
If I blow these LEDs my wife will shoot me 

[sluckey]

You know which end of the battery is +. You know which wire of the wart is +. Get it right.

Amen!

If I blow these LEDs my wife will shoot me

Amen, Amen, Amen!

[ac427v]

Based on my n of 1 I'm questioning that your lights are LED. Batteries in our incandescent window candles lasted 3 days. That's in your ballpark. The LED ones lasted 4 months.
I would much rather work on my next amp than try to fit a wall wart to window candles and deal with related wiring ;-)
-Craig

[shooter]

Why diode?

in the '70s I fixed CB radios for extra money since the Navy didn't pay very well
every car CB had a protection diode, my boss billed that repair at $12.50, gave me $5, when I asked why that much for 15min work, he replied "if they're dumb enough to plug in the CB backward, they're dumb enough to pay 12.50"

[dude]

each take three 1.5v AAA

are the batteries in series, or parallel?
guessing series since you have 4.5v wart, the "Bpack" should have 2 wires, snip them, put a diode, anode at the wart, cathode to Bpack + wire that feeds the lights, wire Bpack - that feeds the lights to wart -

I'm out to lunch again, ha, jut want to get this right: Using a 1N002 diode


Wall wart + wire to anode side of diode, cathode side to + sides of all Bpacks.
Wall wart - wire to all - sides of Bpacks
 
All three candle wired in parallel. 


This prevents "reverse polarity" to the LED lights, possibly blowing them as current flows to + side but will not flow through - side, if polarity is reversed, a safety feature. 

Do I have this right? Too many beers last night


EDIT: going cray here, have other wall warts that put out more vdc then written as output voltage, I'm putting half watt resistors in series on the end of the positive wall wart's lead. Does nothing no matter what size, where is my thinking wrong? I figure I don't want 15vdc going to a 9v pedal, but the voltage stays the same no matter what size resistor I use....?   

[sluckey]

If you put something under 50Ω I bet the voltage will change. 9v @ 50Ω is only 180mA.

[dude]

If you put something under 50Ω I bet the voltage will change. 9v @ 50Ω is only 180mA.

Of course only have 100 ohms and above, but had a 10 ohm 5w cement R, over kill. Had two, 10 ohms did nothing, 20 ohms nothing?


The wall wart I'm using says 500 mA's 9vdc output, but it's 15vdc. ...?

[shooter]

Has switch for 3, 4.5, 6 and 9V. I'll use 4.5vdc out.

does it switch? or is it "stuck" on 15vdc?

take a 10K R and gator clip to the wart + one side R,  - the other side R, measure volts across the R, be quick, she will warm up.

[dude]

 

Has switch for 3, 4.5, 6 and 9V. I'll use 4.5vdc out.

Shooter, I was talking about another wall wart not the candle one. I used the diode per your advice for protection, the candles work perfect, thanks.


I have another wall wary I want to use with a pedal, it's rated 9vdc out and proper polarity but the VDc out is 15vdc. I tried resistors under 50 ohms (as Sluckey suggested) on the positive lead from the wart but voltage never changes. All I had was two 5W, 10 ohms, both 10 and 20 ohms did nothing to this wall wart, rated at 500 mA.


I can't under stand why the resistor doesn't lower the output voltage...? I've tried this on other wall warts and also the same results, what  can I do to lower the dcv voltage to around 9 vs?


I find most wall warts put out 3 to 8 vdc more then the said rating on them..?


Would 15vdc on a compression, reverb, etc  pedal cause damage to the pedals...?


al, (aka the dude)
 

 

[shooter]

glad your wife is happy

why the resistor doesn't lower the output voltage

if the R is in series, and there is little to no current, (load), not much drops, think tube PS without tubes.

Put a "load" on the wart, start with maybe 1k (one lead to +, one lead to -), meter on vdc across the R, does the volts stay 15?

ohm says if I have 9vdc, and .5A  R= 9/.5 = 18ohms, now calc Watts, double it for safety, wart read 9V?, wart smoke?

[dude]

I remember once I had a small Radio Shack transformer that I was using to break in 30 watt speakers, just get them to hum for 48 hours with the correct voltage for the spk wattage, works great. Once I had a 15 watt speaker and didn't want the 30 watt voltage and used a cement R to cut voltage, worked great too but I was measuring the voltage drop when the PT had a load. I keep forgetting about the load...  Again once I was wiring household 120vac current, thought I had the breaker off wiring the receptacle, I didn't but didn't get shocked. Maybe cause there was no load on the circuit...? Had good thick rubber boots, and maybe never touch the neutral at the same time as the positive...? Or probably just lucky...  


I'll try measuring with a load on the wall wart. I have in the past changed polarity on wall warts when I didn't want to cut the supply line, using diodes works great if you can get them open without destroying them. I guess that's the "cheap skate" in me.


thanks