Lundahl Transformers Old Transformer Types Short Description

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
Centertap	pin 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)
Centertap	pin 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

LL2804
LL2804 is yet a microphone input transformer with turns ratio 1+1:7 (200 ohm : 10k) The LL2804 is discontinued and no data sheet is available. For replacements, please look at LL1530 or LL1576.

Pin configuration:
(Transformer seen from pin side. I am afraid I can not tell orientation, as our notes are
incomplete and we have no samples left.)

4,   3,   2,   1


   LL2804
 

8,   7,   6,   5



LL2804 Usage (1:7)
in+	pin 2
in-	pin 3
out+	pin 6
out-	pin 7
Housing 		pin 1
Core 			pin 4
Faraday shield 	pin 5+8

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
```

LL3803
LL3803 is a very low impedance, high current output transformer



2, 	 	1

    LL3803

5,	4,	3



LL3803 Usage (1 : 1.1)
in+	pin 1
in-	pin 2
out+	pin 3
out_ct	pin 4
out-	pin 5

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

LL4604
LL4604 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

LL4901
LL4901 is a 200 ohm : 5 k microphone input transformer, winding turns ratio 1+1:10. The LL4901 is discontinued and no data sheet is available. For replacements, please study LL1538.

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

4,   3,   2,   1


   LL4901


8,   7,   6,   5



LL4901 Usage (1:5)
in+		pin 1
in-		pin 4
connect pis 2 + 3
out+	pin 6
out-	pin 7
ground  pin 5

LL4902
LL4902 is a high turns ratio (1+1 : 22) microphone input transformer with double Faraday shields.
LL4902 was designed for a customer in Australia, and is probably suitable for a 75 ohm : 10k application.
The LL4902 is discontinued and no data sheet is available, but we do actually have approx. 100 x (non-ROHS-compliant) LL4902 in stock.
```
Pin configuration (transformer seen from component side with label readable)

4,   3,   2,   1


   LL4902


8,   7,   6,   5



LL4902 Usage (1:11)
in+		pin 1
in-		pin 4
connect 	pins 2 + 3
out+		pin 6
out-		pin 7
ground 1	pin 5
ground 2 + case and core 	pin 8
```
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

Calrec line output transformer LL5602
LL5602 is a line output transformer designed for Calrec Audio, probably used as a stepup output transformer, turns ratio 1 : 1.6 or 1 : 3.2

Pin configuration (as seen from PIN side)

6,  5,  4,  3,  2,  1






12, 11,    9,  8,  7


Usage (1: 1.6):  
in+	pin 1
in- 	pin 4
connect pin 6 + 3

out+	pin 7 + 12
out-	pin 11 + 8
Faraday shield + housing pin 9




Usage (1: 3.2):  
in+	pin 1
in- 	pin 4
connect  pin 6 + 3

out+	pin 7
out-	pin 11
connect pin 12+8
Faraday shield + housing pin 9

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

Per Lundahl,
Lundahl Transformers AB
Tibeliusgatan 7
SE-761 50 Norrtälje
SWEDEN
Phone: +46 - 176 139 30
Fax: +46 - 176 139 35
Email: