Tesla made a small number of point-contact transistors type xNT40 about which I have no data. I would be very interested to find examples of these, or even just data about them.
If you know anything about these, or have data about them, please
I am also seeking examples of Tesla's point-contact diodes, which are the two series 1NN40 - 6NN40 and 1NN41 - 7NN41. The first series is included in the Hungarian data book linked above. I have not seen an example of these, but old data books show the diagram on the right, which suggests a glass body with a band of rubber or plastic around it.
If you know where I could obtain any, please
This image shows examples from the nNN41 series. They have a typical glass body with a painted stripe around the cathode. The colour code used is a proprietary one:
- 1NN41 = white
- 2NN41 = yellow
- 3NN41 = blue
- 4NN41 = green
- 5NN41 = red
- 6NN41 = black
- 7NN41 = violet
You can find data for these here. The GA20n types use the same colouring but are physically smaller.
There are two more point-contact diodes in the NN41 series that seem to be rare:
- 10NN41 = brown-black
- 11NN41 = brown-brown
These use a longer, thinner case than the lower-numbered NN41 types. Of course, I would be interested to obtain examples.
I would also be very interested to find examples of Tesla's first junction transistors, dating from about 1955. I have an undated page from a Tesla Katalog that lists the PNP types:
- 1NU40 to 4NU40.
- 1NU70 to 4NU70.
- 10NU70 to 12NU70.
- 20NU70 to 23NU70.
- 30NU70 to 32NU70.
If you know where I could obtain any of these, or have data about them. please
Tesla's first production series of transistors is the xxxNU70 series of NPN germanium AF low-power transistors (102NU70 shown):
- 101NU70 - Vce 20 V, Ie 3 mA, 30 mW
- 102NU70 - Vce 25 V, Ie 5 mA, 50 mW
- 103NU70 - Vce 25 V, Ie 5 mA, 50 mW
- 104NU70 - Vce 25 V, Ie 5 mA, 50 mW
- 105NU70 - Vce 30 V, Ic 10 mA, 125 mW, h21e 20-40
- 106NU70 - Vce 30 V, Ic 10 mA, 125 mW, h21e 30-75
- 107NU70 - Vce 30 V, Ic 10 mA, 125 mW, h21e 65-130
There are also 'bílý' versions of 105NU70 to 107NU70 that have lower maximum collector voltage and slightly different gain banding. This word means 'white'. Ivo thinks that this denotes a white spot on the top of the case. This might be a way of selling devics that did not meet the full spec.
- 105NU70 bílý - Vce 15 V, Ic 10 mA, 125 mW, h21e 20-45
- 106NU70 bílý - Vce 15 V, Ic 10 mA, 125 mW, h21e 34-73
- 107NU70 bílý - Vce 15 V, Ic 10 mA, 125 mW, h21e 68-120
The series 151-156NU70 are "high-frequency" ultra-thin-base alloyed transistors used for AM receivers.
It seems that the early production of the xxxNU70 series, including these high-frequency types, used a flat black case like Tesla's first junction transistors. I am very keen to find examples of these.
If you know about the flat can varieties, or can provide data for the high-frequency types, please
There is also a series 101NU71 to 104NU71 of 250 mA types.
- 101NU71 - Vce 30 V, Ic 250 mA, 125 mW, h21e 45-120
- 102NU71 - Vce 30 V, Ic 250 mA, 125 mW, h21e 65-220
- 103NU71 - Vce 48 V, Ic 250 mA, 125 mW, h21e 45-220
- 104NU71 - Vce 20 V, Ic 250 mA, 125 mW, h21e 65-120
There are three series of PNP germanium AF high-power transistors:
Tesla also manufactured germanium types in the GDR GC-, GD-, GF- and GS- series, but using higher serial numbers, as shown by my example of a GS507 (germanium NPN RF low-power) in a plain metal can and a GC519 (germanium PNP AF low-power) in a black-painted one. They also made a small number in the Cyrillic ГТ series.
Tesla copied Western germanium junction transistors in the Mullard/Philips OC series. In the 1968 data book the following are listed:
Tesla went on to manufacture a large number of silicon transistors that do not really interest me. The 1968 Tesla Katalog contains silicon transistors in the standard BC, BD, BSX and BSY series and in the proprietary KC, KF, KD, KU, SU, KFY, KFW, KSY, KSZ, KDY, KUX and KUY series.
Tesla also made germanium diodes in the DDR GA and GAZ series. The image shows a GAZ51 in the ubiquitous TO-1A can; despite the Z this is not a Zener, it is a gold-bonded switching diode.
This unusual construction is the 4GAZ51, a set of four GAZ51 diodes for use in modulators / demodulators. The diodes themselves are unmarked except for some indistinct paint markings. I believe that there is also a dual-diode 2GAZ51 although I have never seen one.
They also copied the Philips/Mullard germanium diodes OA5, OA7 and OA9 (shown) although they did not copy the standard SO-2 glass tube.
They also made silicon diodes in the KY and KYZ series. My image shows a KY701; it is not branded TESLA. Ivo informs me that these were made by Tesla Piešťany in Slovakia from 1967 onwards.
Tesla also made germanium photodiodes:
- 10PN41, 11PN41, 12PN41 and 13PN41
- 10PP41, 11PP41 and 12PP41
My image shows the very thin 10PN40. I am looking for examples of the others.
The 1968 Tesla Katalog contains one silicon photodiode: this 1PP75.
Tesla went on to make many more discrete silicon devices and integrated circuits, which I will not show here.