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audioguru
Nobel Prize Winner
Canada
4218 Posts |
 Posted - Dec 26 2005 : 9:05:57 PM
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Relay vibrators were used in cars long ago because IC square-wave oscillators and high current power transistors weren't invented yet.
You are thinking about re-inventing the wheel.
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John Doe
Apprentece
USA
14 Posts |
Posted - Jan 01 2006 : 10:51:58 PM
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Yes, that is right. In fact, I already have an UPS working as my car inverter; but I was just wondering about if what I told before, would work or not.
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Jan 02 2006 : 12:20:02 AM
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Using a mechanical vibrator instead of a solid-state oscillator will work only until the vibrator wears out. A few minutes? A few hours?
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jreld
New Member
2 Posts |
Posted - Jan 10 2006 : 02:02:20 AM
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Hi, new to the forum, this is just a little off-topic. I just got a catalog with some inverters (12V-120V) in it (for auto/boat/RV). The biggest is 5000 watts. By my crude calculation, that is over 400 amps coming out of the battery. How the heck could you keep the battery charged with that much drain? Thanks
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Jan 10 2006 : 05:25:07 AM
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A 5kW inverter is for a big sailboat. It has a huge wind-generator and the inverter is used when there isn't wind. A single battery would explode from the high current so many batteries are in parallel and used as ballast in the keel.
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naseerak
New Member
2 Posts |
Posted - May 22 2006 : 01:40:42 AM
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quote:
Very popular topic.. Looks like people have problems with this device.
I was wondering about this schematic. Just a mental exercise, you know. What caught my attention is the fact that both tantalum caps showed in - as I think - reversed polarity.
Look at the schematics: the base of the transistor never gets more than 1V above emitter voltage - when the transistor is opened; when the transistor is closed, the base voltage may go well below 0.
The other side of the cap is connected to collector. When transistor opened, it goes to almost 0; but when it is closed, it goes well above 12V (without a diode; 13V with a diode in place).
Therefore, I would connect minus of the caps to bases and plus to collectors. BTW, blowing caps may be just a sequence of wrong polarity..
So, my advice would be - change caps polarity.
Opinions are welcome.
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - May 22 2006 : 06:40:08 AM
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Hi Naseerak,
Yes the capacitors are shown with backwards polarity.
But they charge to a voltage that is nearly double the supply voltage due to center-tapped transformer action. Then when one side of the capacitor is driven very negative, the base-emitter junction of the transistor has its max reverse voltage rating of only 7V far exceeded. The junction behaves like an extremely high current zener diode when it has avalanch breakdown and the extremely high current pulses in the capacitors blows them and wastes a lot of power.
The transistors don't have enough base current to develop much power anyway.
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anton
New Member
1 Posts |
Posted - Jun 14 2006 : 3:57:02 PM
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hi i have builde this inverter and powerup a 100wat bulb with 4.5ampere battery. just use this cuircut http://www3.telus.net/chemelec/Projects/Inverter/Inverter.png it is similar to the cuircu that posted on aarons page but the caps are conected with the minus together to make one biopolar cap with lower capacience .for the transformer i use a 700va transformer from burned UPS so good luck and sory about my englihs im Russian
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Jun 14 2006 : 4:17:44 PM
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That circuit has the same problems as this one:
1) The emitter-base junctions of the transistors have avalanche breakdown.
2) The 180 ohm resistors don't supply enough base current to the transistors.
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WaasiL
Apprentece
5 Posts |
Posted - Jun 15 2006 : 07:58:45 AM
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Hello to all.
What could be the easiest inverter to build? In a matter of parts and simplicity?
Waasil
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Jun 16 2006 : 5:07:04 PM
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This one is simple and easy:
A Cmos CD4047 oscillator needs just a resistor and a capacitor to make a low frequency perfect square-wave and also has an inverted output to drive a push-pull pair of darlington transistors or Mosfets to drive a center-tapped stepup transformer.
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WaasiL
Apprentece
5 Posts |
Posted - Jun 17 2006 : 01:45:10 AM
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Thanks allot audioguru for your reply.
1-What could be the wattage of that inverter?
2-Where can I get its schematic.
By the way, is it possible to use small normal transformer ( the ones which are in radios) just to test the inverter if it is working or not before buying a large transformer?
Please help me.
Thanks in advance.
WaasiL
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abdo_87
New Member
Libya
2 Posts |
Posted - Jun 17 2006 : 04:37:52 AM
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hi to every human in here,please could any body send me information about simple electronic transmitter
asd |
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Jun 17 2006 : 08:06:21 AM
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quote:
1-What could be the wattage of that inverter?
About 150W with a pair of darlington output transistors, or about 1kW with a pair of modern Mosfets. I saw a very powerful inverter that used 16 Mosfets.
quote:
2-Where can I get its schematic.
It is simple. Draw it yourself. Copy a Chinese one.
quote:
By the way, is it possible to use small normal transformer ( the ones which are in radios) just to test the inverter if it is working or not before buying a large transformer?
Yes, but it won't prove anything except that the oscillator works. You can test the oscillator without a transformer.
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Jun 17 2006 : 08:10:58 AM
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quote:
hi to every human in here,please could any body send me information about simple electronic transmitter
This topic is about the inverter project, not about a transmitter.
You can find out information and find FM transmitter projects in Google.
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Topic |
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12/120V inverter again
