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 12/120V inverter again
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - May 27 2008 :  08:22:37 AM  Show Profile  Reply with Quote
The ferrite core for the high frequency transformer might be difficult to find or impossible to buy.
Maybe you must buy a cheap Chinese pure sine-wave inverter and use its transformer.
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - May 27 2008 :  08:26:56 AM  Show Profile  Reply with Quote
Wasssup.........Johnny
Do you have the schematic diagram of the sine wave inverter that you are talking about????



juan dela cruz
Penniless INVENTOR
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wasssup1990
Nobel Prize Winner

A Land Down Under
2261 Posts

Posted - May 27 2008 :  09:32:58 AM  Show Profile  Visit wasssup1990's Homepage  Reply with Quote
quote:

From Audioguru:
The ferrite core for the high frequency transformer might be difficult to find or impossible to buy.


Yeah I think that might be the highest hurdle to jump over, but I have a few ideas. Keeping them to myself for now.

quote:

From Juan:
Do you have the schematic diagram of the sine wave inverter that you are talking about?


No, I haven't designed it yet. I better not get sidetracked too much, I have two projects underway. The sinewave inverter will be a switch from the kind of projects that I am currently doing and it'll be fun and very usefull.



When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion.
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - May 29 2008 :  04:13:14 AM  Show Profile  Reply with Quote
Wasssup...johnny

Are you done with your sine wave inverter's schematic diagram?????

juan dela cruz
Penniless INVENTOR
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wasssup1990
Nobel Prize Winner

A Land Down Under
2261 Posts

Posted - May 29 2008 :  06:00:36 AM  Show Profile  Visit wasssup1990's Homepage  Reply with Quote
No Juan. I said I have two projects underway and I shouldn't get sidetracked. It'll be a long time before I can put pen to paper for a sinewave inverter. See you!

When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion.
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - May 29 2008 :  06:58:27 AM  Show Profile  Reply with Quote
quote:
Originally posted by wasssup1990

No Juan. I said I have two projects underway and I shouldn't get sidetracked. It'll be a long time before I can put pen to paper for a sinewave inverter. See you!



Sorry for disturbing you Johnny

.........Do you know where can I find a schematic diagram of a TELEVISION aerial Signal Amplifier or VHF/ UHF amp. w/ a boost gain of Approx. 50dB?????

I've search in google and I found ckts w/ low gain(i.e. 10dB-20dB)

Thanks pal

juan dela cruz
Penniless INVENTOR
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wasssup1990
Nobel Prize Winner

A Land Down Under
2261 Posts

Posted - May 29 2008 :  10:00:29 AM  Show Profile  Visit wasssup1990's Homepage  Reply with Quote
I could only find 20dB.
http://www.electronics-lab.com/projects/rf/003/index.html
http://www.newcircuits.com/project.php?id=prjsub003
http://www.elecfree.com/electronic/tv-signal-amplifier-by-bfr90-bfr91-bfw92/

When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion.
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pebe
Nobel Prize Winner

United Kingdom
1078 Posts

Posted - May 29 2008 :  12:53:24 PM  Show Profile  Reply with Quote
quote:
Originally posted by JUAN DELA CRUZ
.........Do you know where can I find a schematic diagram of a TELEVISION aerial Signal Amplifier or VHF/ UHF amp. w/ a boost gain of Approx. 50dB?????

That's a voltage gain of around 300 times. You would have a job keeping such a beast tame in a single unit!

Where would you use such an amplifier?
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - May 29 2008 :  6:45:11 PM  Show Profile  Reply with Quote
A TV that works properly is extremely sensitive. If it doesn't pick up a clear signal with a good antenna then the transmitter is too far away. An amplifier will just amplify its own noise.
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pebe
Nobel Prize Winner

United Kingdom
1078 Posts

Posted - May 30 2008 :  2:35:26 PM  Show Profile  Reply with Quote


quote:
I've already searched those ckts. & as a matter of fact I'm already using this ckt.(below) for a long time. The downside of this ckt is that it has less selectivity(i.e.less channel/station). http://www.elecfree.com/electronic/tv-signal-amplifier-by-bfr90-bfr91-bfw92/

Its stated output of 90uV is in error - and means nothing. But its an ultra broadband amplifier that's wide open to interference and will give a poor signal/noise ratio over any narrow band of frequencies for which it will be used.
quote:
I live in a country where typhoon visits regularly that knock-out power lines, cable system including TV aerial antenna. That's the reason why I need to boost the aerial signal for my TV.
Under those circumstances, TV reception would be the least of my worries.
quote:
I've ask this question already in another electronics forum website and they said building an aerial amp w/ such huge gain(50dB) will result for noise to be amplified also that won't benefit apprently right????
Absolutely correct.
quote:
I think I'll need to make a shorter aerial antenna*(PASSIVE) instead....but its gain will be lesser than the longer one. How about a home-made CABLE system????...Do you think its possible??????
A TV antenna is essentially a resonant half wave dipole matched to a 75ohm coaxial cable. It should feed into a matching 75 ohm load at the receiver or amplifier. I doubt the circuit you referred to will give a match anything like good enough.

Cable TV is an art in itself. It requires amplifier design and output distortion levels low enough to limit intermodulation and cross modulation to acceptable levels. It is not a practical task for a DIY enthusiast.
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ElectroEgg
Apprentece

Trinidad and Tobago
7 Posts

Posted - May 31 2008 :  12:55:06 AM  Show Profile  Reply with Quote
Helloooo. The topic here is about inverters. Is there anyone who can make adjustments to this square wave inverter circuit to produce a modified sinewave?

Download Attachment: 100w square-wave inverter.gif
15.86 KB

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pebe
Nobel Prize Winner

United Kingdom
1078 Posts

Posted - May 31 2008 :  01:20:57 AM  Show Profile  Reply with Quote
You might find help in this thread.

http://www.aaroncake.net/forum/topic.asp?TOPIC_ID=7123&whichpage=2
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ElectroEgg
Apprentece

Trinidad and Tobago
7 Posts

Posted - Jun 01 2008 :  6:44:40 PM  Show Profile  Reply with Quote
Hi Jaun. Thanks for the schematic. I would update you on my progress.
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Saso
New Member

Slovenia
3 Posts

Posted - Jun 03 2008 :  3:48:41 PM  Show Profile  Reply with Quote
I have built 500W inverter with CD4047 and 2N3055 transistors. If I connect it to my desktop power supply it works relatively OK but if I connect it to car battery it does not work there is no output, CD4047 dies and transistors and 10W resistors heat up.
When it is connected to desktop supply and it works the measurements are (for instance):
- Power supply 13V, 4A
- AC output 110 V
- DC output (after diode bridge and capacitors) 95V, 0,48A
It works fine with heavier load also. Highest reading was almost 10A input and 1A output. That is as high I can go with this power supply.
My transformer is 13,8-0-13,8/110V.
I have tried everything I could think of according to my limited knowledge of electronics.
Would you be so kind and help me to solve this problem - why it does not work with the battery.
Saso
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audioguru
Nobel Prize Winner

Canada
4218 Posts

Posted - Jun 03 2008 :  7:15:59 PM  Show Profile  Reply with Quote
Hi Saso,
You forgot to post the schematic of your 500W inverter.
Its CD4047 needs to be fed through a 100 ohm resistor then a 15V zener diode to ground to protect it from spikes.
Your power supply has an output of only 13V x 4A= 52W. A 500w inverter needs an input of 600W. A huge difference.
The voltage rating of your transformer is wrong. The RMS voltage at the output of yje inverter is probably a lot lower than an ordinary meter measures its square-wave.

Post the schematic and we will fix it for you.
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