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Author Topic: 110v lawn mower power rectifier  (Read 2679 times)

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Offline mr_shaferTopic starter

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110v lawn mower power rectifier
« on: May 03, 2008, 04:00:15 PM »
I am converting an old battery-powered black&decker mower to run on 110vac.
The mower motor is 24vdc which ran on two 12v batteries. 
My junk box produced a RadioShack 30?amp bridge rectifier which outputs plenty of DC but nearly 100volts .... which makes a screamin' leaf blower, but I wanna cut the grass !

How do I tame this beast down to 24vdc ?

Offline benji

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Re: 110v lawn mower power rectifier
« Reply #1 on: May 03, 2008, 04:34:58 PM »
to tell u to use a voltage divider would be a lose of power
maybe you can use  large resistor values, somthing like 100k
so 100v/100k = 1mA which is fine as a lose
not sure if there is a better way to do this
good ol' BeNNy

Offline TrickyNekro

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Re: 110v lawn mower power rectifier
« Reply #2 on: May 03, 2008, 05:04:13 PM »
man... no...
100k is way too much... way too much...
Resistor is not an option here... but I haven't understand what you want...
To want 100V to 24V both DC or
100V to 24V both AC...
The first... well don't even think it...
The second not only it's possible... but it's hell easy!!!
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline pomprocker

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Re: 110v lawn mower power rectifier
« Reply #3 on: May 03, 2008, 06:30:05 PM »
just get an old laptop power supply or something
http://www.trcelectronics.com/24-volt-power-supplies-low-external.1.shtml


otherwise you need a step down transformer and a bridge rectifier and a smoothing capacitor.

Offline benji

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Re: 110v lawn mower power rectifier
« Reply #4 on: May 04, 2008, 09:36:23 AM »
Quote
To want 100V to 24V both DC
i guess thats what he ment,, cause in case of ac he can just hook a trans.

but whats wrong with resistors? there are high watt ones
can u explain whats the abd thing with resistors?
good ol' BeNNy

Offline TrickyNekro

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Re: 110v lawn mower power rectifier
« Reply #5 on: May 04, 2008, 03:03:13 PM »
They are not practical let's say for many reasons...
Let's say he operates the machine around 2 - 3 Amber... This means a nearly 80W resistor...
An 80W resistor is by all means huge...

This DC step down is usually done with MOSFETs and PWM...

It's possible... but not for a beginner since he uses high voltage... which can be dangerous....


Lefteris
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

 


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