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Short descriptions of some old Lundahl transformer types

I have some LL1515. What is it and how can I use it? LL1515 is a microphone input transformer with turns ratio 1+1:7 (200 ohm : 10k) The LL1515 is discontinued and no data sheet is available. For replacements, please study LL1530 or LL1576.

Pin configuration (transformer seen from component side with label readable)

4, 3, 2, 1 LL1515 8, 7, 6, 5 LL1515 Usage (1:7) in+ pin 1 + 3 in- pin 2+4 out+ pin 6 out- pin 7 ground pin 5

Is there a data sheet for the LL1518? No, I am afraid we have no data sheet for the LL1518. The LL1518 is a (solid state) line output transformer, similar to the LL1517. Usage:

Turns ratio 1:1 In+ pin 1 (left bottom, if you read transformer label

correctly) In- pin 5 Out+ pin 7 Out - pin 10 (right top) Connect pin 6 + 9 Ground pin 8 Turns ratio 2:1 In+ pin 1 (left bottom, if you read transformer label

correctly)

In- pin 5 Out+ pin 7 + pin 9 Out - pin 10 + pin 6 Ground pin 8

LL1521 The LL1521B is a high impedance line input transformer, very similar to the LL1540 but with a slight stepup. Turns ratio 1 + 1 : 2.28

Usage: In+ pin 1 (left row, bottom pin when viewed from

component side) In- pin 3 connect pin 2 + pin 4 Out+ pin 5 (right row, bottom pin when viewed from

component side) Out- pin 8 Shields pin 6

LL2603 The LL2603 is a small size line isolation transformer, similar to the LL1532 Turns ratio 1ct : 1

Usage: In+ pin 1 In- pin 4 Centertappin 2 Out+ pin 6 Out- pin 7 Faraday shields pin 5 + 8

LL2613 The LL2613 is a small size microphone input transformer Turns ratio 1+1 : 10

Usage: In+ pin 1 (coil 1) and pin 4 (coil 2) In- pin 2 (coil 1) and pin 3 (coil 2) Centertappin 2 Out+ pin 8 Out- pin 6 Faraday shields pin 5

I have some LL2801. What are they used for and is there any datasheet available Sorry, but there is no data sheet for the LL2801

LL2801 is a 600 ohm output transformer, turns ration 1:1 Core: Radiometal lamination, ED style. Usage:

in+ 7 in- 6 out+ 9 out- 10

LL3802 General purpose isolation transformer. LL3802 is a "600 : 600 ohm" general purpose isolation transformer, turns ration 2:1+1 Core: Mu metal, ED style.

Usage 1:1 in+ 7 in- 9 out+ 1 out- 5 connect 2 + 4 Faraday shield 10 + 6 Usage 2:1 in+ 7 in- 9 out+ 1+4 out- 2+5 Faraday shield 10 + 6

LL3814 The LL3814 is a C-core line output transformer, turns ratio 3 + 3 : 1+1

Usage, 3 : 2 In+ pin 1 + pin 6 in- pin 3 + pin 4 leave pin 2 + pin 5 Out+ pin 7 Out- pin 11 Connect pin 12 + pin 8 Ground pin 10 no pin at 9

LL3815 LL3815 is a small mu metal core microphone / line input transformer, turns ratio 1+1 : 5

Usage, 1 : 5 In+ pin 1 + pin 4 In- pin 2 + pin 3 out+ pin 8 out- pin 6 Shields pin 5 no pin at 7

LL3817 The LL3817 is identical to LL3814 (above), except that height is 1 mm less.

I have some LL4202. What is it and how can I use it? LL4202 is a high level mu metal core output transformer, turns ratio 1:1.

Usage: in+ pin 1 in- pin 2 out+ pin 6 out- pin 5 Shields pin 4

How can I use the LL4501? The LL4501 is a C-core line output transformer. Standard version is gapped for DC current. LL4501G is gapped for a smaller current and has been used in telephone hybrid circuits

Pin configuration (as seen from PIN side) 4, 3, 2, 1 8, 6, 5, LL4501 usage (turn ration 1 : 1) pin 1 primary signal in (+) pin 3 primary side ground pin 2 + pin 4 connect pin 8 out + pin 6 out - pin 5 Faraday shield. Ground.

What is LL4601 LL4601 is a high impedance line input transformer, 2:1+1

Pin configuration (as seen from PIN side) 4, 3, 1, 8, 7, 6, 5, Usage (1:1): in+ pin 8 in- pin 5 connect pin 6 + pin 7

out+ pin 4 out- pin 3 Faraday shield pin 1

How can I use the LL4602? The LL4602 is a C-core line output transformer for unbalanced (single-end) drive. Internal structure is similar to the LL5402.

LL4602 usage (turn ration 1 : 1) Pin 1 + Pin 5 primary ground pin 2 + pin 4 primary signal in (+) pin 3 not used pin 7 out + pin 10 out - pin 6 + pin 9 connect

Line input transformer LL4603 LL4603 is an improved LL4601, normally used 1 : 1

Pin configuration (as seen from PIN side) 4, 3, 1, 8, 7, 6, 5, Usage (1:1): in+ pin 8 in- pin 5 connect pin 6 + pin 7 out+ pin 4 out- pin 3 Faraday shield pin 1

Pin configuration and data for LL4604? What is it and how can I use it? LL4204 is a general purpose isolation transformer with a mu metal lamination core. Turns ratio 1+1 : 1ct.

Usage: in+ pin 1 in- pin 2 in+ pin 4 in- pin 5 (Pins 1, 2, 4, 5 can be used in series or in parallel) out+ pin 7

out centertap pin 3 out- pin 9 Shields pins 6 and 10

I have some output transformers LL5008. Is there a data sheet? LL5008 is a low profile, low leakage inductance line output transformer. Connections are made through short flying leads and not through pins. This was a solution to save board height. I am afraid we have no data sheet for this type. For similar function, please study the LL1524 or LL7401.

Pin configuration (transformer seen from side of flying leads) 1 5 2 6 3 7 4 8 LL5008 usage (1:1) in+ pin 2 in- pin 4 connect pins 1+3 out+ pin 6 out- pin 8 connect pins 5+7

Line output transformer LL5011 LL5011 is a pin version of LL5008, normally used 1 : 1 Very low leakage inductance.

Pin configuration (as seen from PIN side) 5, 4, 3, 2, 1 10, 9, 7, 6, Usage (1:1): in+ pin 1 in- pin 4 connect pin 2 + pin 5 out+ pin 10 out- pin 7 connect pin 9 + 6 Pin 3 not connected

You have a data sheet for LL5801? LL5801 is a 1+1 : 2 audio isolation transformer originally designed for Kungliga Dramatiska Teatern (Royal Theater) in Stockholm. Sorry, no data sheet. A modern replacemen is LL1527 or LL1588. LL5801 pinout and usage:

Pin configuration (transformer seen from component side with label readable)

4, 3, 2, 1 LL5801 8, 7, 6, 5 (I am sorry, but I am unsure about orientation, as we have no samples

left in stock. There is connection between pins 1 and 2, but not between pins 5 and 6) LL5801 Usage (1:1) in+ pin 1 in- pin 4 connect pin 2 + 3 out+ pin 6 out- pin 7 ground pin 5+8 (Faraday shield)

SR501 SR501 is a high level 600 ohm : 600 ohm isolation transformer

in+ 1 in- 5 out+ 7 out- 9 Faraday shields 6+10

SR502 SR502 is a high impedance bridging input transformer

in+ 1 in- 5 out+ 7 out- 9

Faraday shields 6+10

SR503 SR503 is a line output transformer with turns ratio 1.4 : 1

in+ 8 in- 6 out+ 10

out- 4

SR504a och SR504 SR504A is a microphone transformer 200 ohm : 2k

in+ 2 in- 3 out+ 6 out- 7 core 1 Housing 4 Faraday shield 5

SR504a is similar to the more modern transformer LL1538

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Per Lundahl, web_master/AT/lundahl/DOT/se Lundahl Transformers AB

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