Looking for Data on transistor OC940

Hello Hobbyists and Enthusiasts,

I am looking for data on an old transistor type OC940. I think it is made by Philips.

I had a search around the web with no luck, perhaps some of you may have some old transistor Data books from the 60's and 70s.

I know it is a high voltage transistor but I was just wondering if there was anything special about it having low inter-electrode capcitance or anything like that. This OC940 is Q9 in an old BWD 502 oscilloscope.

The mention of the giveaway BWD 502 upthread has re-kindled my interest to try and get it working properly for my friend since he has thrown some time and money at it. I spoke to McVan instruments but no luck there.

While speaking to a very helpful chap at McVan, I mentioned a missing switch on the trigger pot that is different from the schematic I have and the unit. He explained the pot was dismantled by BWD, a drop of arldite was then placed at the end of the pot track to lift the wiper and act as a switch. How is that for tricky! Heh heh heh.... I would never had known!

There is no urgency here, just nice to get an old CRO working a bit better than it is at present. Thanking you in advance.

Regards, John Crighton Hornsby

Reply to
John Crighton
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There's a blast, from the past

try searching for "germanium transistors oc"

Reply to
Tony Maher

Are you sure it is OC940? Could it be OC440? My old Philips short form catalog lists OC140 and Mullard lists a OC440.

OC440 is, I believe, a pnp high speed switch and according to Mullard is equiv to OC203 which they say has Vce=60V. Unfortunately, I have no other info.

Reply to
Ross Herbert

"John Crighton"

** I bet the BF336, 337 or 338 would be suitable equivalents - all in TO39 ( TO5 ) packs.

These are rated at 185, 250 and 300 volts, with an 80 to 160 MHz Ft.

WES sell the latter two for a $1.45 and $1.25 each.

BWD used the BF 336 in several models, like the 539B.

.......... Phil

Reply to
Phil Allison

Hello Ross, according to the manual that I have for this old BWD 502 scope, transistor Q9 is an OC940 but on the same line in the manual DC940 is used. OC940 is used on the schematic. To add more confusion the chap at McVan said it was a silicon type. Just like Tony Maher, I assumed Germanium.

The ring in transistor that is fitted to the Q9 spot is a silicon. The original is long gone. The scope is 35 years old. If this Q9 transistor should be a germanium type and a silicon type is fitted then that would not be good. Just for fun I will try fitting a germanium type.

I am following this repair up out of interest only. I will ask the chap who is giving away a BWD 502 in the other thread "Free CRO to good home" what the type number of transistor Q9 is. Maybe he has a few minutes to take the covers off and take a look.

Thanks for looking up your data books Ross, much appreciated.

Regards, John Crighton Hornsby

Reply to
John Crighton

"John Crighton"

** Lots of later OC type numbers were silicon !!!

Check OC200, 201, 202 and 203 for examples.

All low voltage silicon PNPs from Philips /Mullard.

.......... Phil

Reply to
Phil Allison

Hello Phil, thanks for that information. Impressive specs and cheap, I'll pick up a few. I have a 539D. Still works fine.

I was just mentioning to Ross that I am not sure if the OC940 or (DC940) is silicon or germanium.

Phil, remember some time ago you sent me a file of a schematic for a BWD820. Well, today I picked up another old BWD820 for my friend who owns this poor performing BWD502. This 820 has dirty pots and intermitant switches. Definitely a goer with a bit of carefull cleaning, which my friend is capable of doing. So he now has an upgrade from a 10 Mhz scope to a 25Mhz scope. The University of technogy Sydney (UTS) are disposing of their old scopes of various models, but I picked the faulty 820 because I had a schematic for it, courtesy of you. I thought you might like to know that bit of trivia :-)

A reader of this group put me on to the scopes for sale at the UTS. (Thanks "A" )

Regards, John Crighton Hornsby

Reply to
John Crighton

Hello Tony, no luck on that tack either. Regards, John Crighton Hornsby

Reply to
John Crighton

Hello Phil, yes, I have just been reading about the origins of the European type number system. O for zero heater volts and C for transistor and then how every transistor would start with OC. Changes had then to be made. Interesting reading......I look for something and spend lots of time reading other stuff. Takes me ages to find a word in the dictionary because I check out so many other words first. Heh heh heh Regards, John Crighton Hornsby

Reply to
John Crighton

From memory "C" means a three element device (triode in valve terminology) "A" = diode "B" = double diode (I think). So germanium or silicon diodes were OAxx, transistors OCxx.

The correlation in valves were things like ECC83 which was "E" = 6.3v heater "CC" - double triode, etc.

Hope my memory is not failing too much!

Alan

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Reply to
Alan

the first transistors I ever used were AC128's.

Cheers Terry

Reply to
Terry Given

"Terry Given"

** I can beat that.

I used my first OC71 as a phototransistor by scraping the black paint off the case !

After a long stint with valves like the 6V6, 5Y3, 6AC7, 6BE6, 12AU7 and

12AX7 - I moved onto 8 watt audio amplifiers employing the AD161 / 162 output pair with AC127 and AC 128 as drivers.

Geraniums did "wilt" rather easily so in the very late 60s, when silicon types like the BDY20 & 2N3055 appeared, along with the 40409 / 40410 & TT800 / TT801 driver pairs, I reckoned we were finally onto something.

........ Phil

Reply to
Phil Allison

Yep, I remember the "good 'ol" days (or was it the bad old days) too. Used an OC71 as a single stage audio amplifier for a crystal set when in late primary school. :( Gee seems like an eternity ago!

The following year in high school I built a regenerative detector AM radio that used an OC45 in the RF stage followed by an OC71 audio amplifier. A chance to recycle some of the components. And yes they were expensive back in those days when you had to finance your electronics projects from pocket money :(

After that came the AC125 (close enough T01 equivalent to the OC71) and the AC126 (less c-e leakage and a slightly higher operating frequency capability) and of course the AC127 / AC 128 used in simple complimentary symmetry output stages (with flag heatsinks bolted to a strip of aluminium for a whole whopping 300mW output at 10% THD.

I also had a handful of GET104 transistors made by G.E.C. They were PNP Ge types. Got no idea how old they were. Also some Telefunken AF117 (circa

1960).

Things have sure come a long way since then.

Cheers, Alan

Reply to
Alan Rutlidge

Ahhh the good old days. My first was a single transistor radio I built using an OC44 - later I added an OC74 (Ithink it was) to give a bit more volume

David

Terry Given wrote:

Reply to
quietguy

Howdy,

According to the schematics for the BWD502, Q9 reads as BC940.

Reply to
Man Without Pigs

Hello MWP, I may be getting somewhere now. I have model 502 s/n 5669 My schematic is for s/n 7129 and above. (the wrong one) dwg 620A

Is your schematic dwg number 620 for serial numbers below 7129 ? If so, may I have a copy or scan? Your out of pocket expenses will be gladly fixed up.

Regards, John Crighton

18 Talwong Street Hornsby Heights NSW 2077
Reply to
John Crighton

How close does a BC558 or PN2222 come to that??

Reply to
The Real Andy

"The Real Andy"

** The TO-18 (small metal) series of silicon NPN transistors BC107, 8, 9 were released here in the late 1960s - with gold plated leads. Then came the similar PNP series of BC 177, 8 , 9.

Then the SOT-25, angular plastic versions BC147, 148, 149 etc appeared a year or so later.

Then there were the TO-106 "dome top" versions BC 207, 8, 9 etc.

Then finally the TO-92 versions, BC 547, 8, 9 & BC 557, 8 , 9.

The PN.... series appeared in the mid 1970s, IIRC - as plastic versions of some previous 2N.... prefix devices.

It was a regular silicon device invasion in the late 60s and early 70s !!!

........... Phil

Reply to
Phil Allison

Serial number is 16572. Drawing number is 1194. I'll copy it and post it up.

Reply to
Man Without Pigs

Hi, the serial number is much higher but I am still interested to see the schematic. Thanks for that.

When Michael, the new owner starts repairs we might be able to compare waveform and voltage readings to help each other. Regards, John Crighton, Hornsby

Reply to
John Crighton

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