Hello mentors,
Please I am building on my basic in electronics. Now, I have reached a chapter to learn to match impedance using transformer. So the material needed is a small impedance matching transformer approximately 600 to 800 ohms and 4 to 8 ohms speaker. Can someone tell me how to get or build the special type of transformer since I can get it here in the market.

 

5Pcs 1300 : 8 Ohm Audio Transformer EE14
$1.47
Turns ratio is 12.75 : 1


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ADDED:
Audio transformer 42TL008-RC
Price: 2,34 €


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5Pcs 1300 : 8 Ohm Audio Transformer EE14
$1.47
View attachment 329859

Thanks Danko. As highlighted in the question, I need resistance between 600 to 800 ohms not 8 ohms.

 

https://cpc.farnell.com/eagle/p037u/100v-transformer-16w/dp/LS01706

 

I'll also add
https://airlinktransformers.com/pro...toroidal-transformer-standard-range-cm0080224
provided that a frequency response of 50Hz to approx. 1kHz would do.

 

Amplifiers used input and output transformers about 70 to 80 years ago.
Most amplifiers that can drive an 8 ohms speaker can drive a 4 ohms speaker with a higher output power.

 

Amplifiers used input and output transformers about 70 to 80 years ago.
Most amplifiers that can drive an 8 ohms speaker can drive a 4 ohms speaker with a higher output power.

That's the same age as the teaching material for some basic electronics courses.

 

All of the equations remain the same for basic electrical circuits. The laws of physics relationships do not change. Of course, new devices arrive and the frequencies able to be used continue to increase.
But the circuit analysis, the relation of voltage and current and power have not changed. Likewise, the effects of inductance, capacitance, and resistance are still the same. So the basics that applied 50 years ago still all hold.

What does change are the available components, both the passive devices and especially the active devices.
Especially the programmable logic systems, including the processors. And in that area, along with the constantly advancing abilities, comes the ability to have program bugs that are more subtle and much more challenging to deal with.

The usefulness of transformers remains, although alternatives have been created that in many applications are suitable replacements. The primary drive towards avoiding transformers has been the cost and size. While other components constantly shrink, transformers have not been economically following the trend so much. And for convenient impedance matching with isolation and power handling ability, the alternatives are not nearly as convenient.

 

I want to thank you all for your response. Nonetheless, I cannot order the part in the link because they don't have store here. What old appliances can I get them from?

 

I want to thank you all for your response. Nonetheless, I cannot order the part in the link because they don't have store here. What old appliances can I get them from?

100V-line public address speakers between 10W and 20W.

 

Audio output transformers are usually single-application items used in audio amplifiers. Ten to 20 watt units would be found primarily in much older tube-type audio equipment. They will probably require rewinding the primary side to be useful with transistor circuits.

 

Audio output transformers are usually single-application items used in audio amplifiers. Ten to 20 watt units would be found primarily in much older tube-type audio equipment. They will probably require rewinding the primary side to be useful with transistor circuits.

Valve amp output transformers are typically between 4kΩ and 10kΩ on the primary side. A lot more than the TS's target of 600Ω to 800Ω.
Some of them are gapped to work with a standing DC current.

 

Valve amp output transformers are typically between 4kΩ and 10kΩ on the primary side. A lot more than the TS's target of 600Ω to 800Ω.
Some of them are gapped to work with a standing DC current.

That is exactly why I commented: " They will probably require rewinding the primary side to be useful with transistor circuits. " (Clearly stated in post #11)

 

"What old appliances can I get them from? "

Usually from this kind of deceased junk :



And highly probable from inside a 120 to 12 V :

Audio impedances are referred to 1KHz. Read carefully; impedance is one thing, resistance is another.

 

Any transformer with a ratio of √(800/8) which is 10:1 will do, provided that it has enough magnetising inductance to manage the lower end of the frequency response, and low enough leakage inductance to manage the higher end.
So a 120:12 transformer would do the job, in theory. If it were rated for 60Hz. As magnetising inductance varies inversely with power, a lower powered transformer would have better low-frequency response (and worse high frequency response).
Most mains transformers have an adequate response at 1kHz, though it might be pushing it a bit for split-bobbin types.

 

"What old appliances can I get them from? "

Usually from this kind of deceased junk :
View attachment 330014


And highly probable from inside a 120 to 12 V :
View attachment 330013
Audio impedances are referred to 1KHz. Read carefully; impedance is one thing, resistance is another.

It is not likely that any of those devices have audio transformers able to handle even one watt. And the TS was specific: ten to 20 watts.
If the TS was nearby I could give them a 100 watt output transformer from a BOGEN PA amplifier. But shipping to the TS listed address would be terribly expensive. Probably Digikey would sell it but again, the shipping will be the problem.

an explanation of the actual purpose may lead to an alternative solution being found. so I suggest that the TS explainthe goal of the search.

 

I cannot order the part in the link because they don't have store here.

Oh, I see...

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Hubtecs Electronic Component Store
Electronic parts supplier
Address: 315 Herbert Macaulay Wy, Yaba, Lagos 101245, Lagos, Nigeria
+234 813 501 0778
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New Nigeria electronics
Electronic parts supplier
Address: 135 MOHAMMED MUSTAPHA WAY JIMETA YOLA, ADAMAWA STA#TE, Jimeta 640102, Nigeria
-----------------------------------------
Ibekwe Electronics Nigeria
Electronic parts supplier
Address: Shop F2,Ogbete Main Market, Nigeria
+234 803 713 4624
-----------------------------------------
Uncle Laga Nigeria Enterprises
Electronic parts supplier
Address: 28,Odelemo Road, Nigeria
+234 802 389 5772
-----------------------------------------
Flamingo Electronics and Multi-Purchase Store
Electronic parts supplier
Address: F3WJ+JQV, Umuoba Uratta Rd, Ikenegbu, Ihitta 460104, Imo, Nigeria
-----------------------------------------
Ganic Electronic Nigeria
Electronic parts supplier
Address: Block B33, Oshodi Main Market, Oshodi, Oppsoite Shop No. C8, Lagos, Nigeria
+234 803 552 8769
Service options: Offers same-day delivery
-----------------------------------------
Nnabest Electronics Nigeria
Electronic parts supplier
Address: 54 Abakpa Nike Rd, Isowopo I 342101, Ondo, Nigeria
+234 703 534 9741
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Authentic Power Nigeria International
Electronic parts supplier
Address: 33,New Market Road, Nigeria
+234 806 097 9679
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Uba Na Bombey Nigeria Limited
Electronic parts supplier
Address: Blk 4, Shop 9,Akeju Shopping Complex, Nigeria
+234 805 467 8305
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Blessed Wisd Chibuzor Electronic Nigeria
Electronic parts supplier
Address: Oshodi Main Market, B14 Opposite A19, Oshodi, Lagos, Nigeria
+234 703 512 2339
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Onyisco Electrical Nigeria Service
Electronic parts supplier
Address: 2 Cooke Rd, Avbiama, Benin City 300102, Edo, Nigeria
+234 803 067 9445
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Sole Electrical Nigeria Limited
Electronic parts supplier
Address: 21 Tatlow Road, Ezinihitie Mbieri 461121, Imo, Nigeria
+234 803 395 7886
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Kenelectronics Nigeria
Electronic parts supplier
Address: 105,Adesuwa Grammar Road, Nigeria
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De Onward Nigeria Limited
Electronic parts supplier
Address: 4/5 Ahmadu Bello Wy, Kado, Mobushipe 900108, Federal Capital Territory, Nigeria
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OBINWANNE & PURITY NIGERIA
Electronic parts supplier
Address: C1-12 Arena mkt oshodi, Lagos 300001, Nigeria
+234 803 528 0202

 

I bet this company might have a 100V-line transformer.

 

OK, there you go!! A whole bunch of distributors.
The great thing about these forums is the vast resource of knowledge and experience that is available.