Rangemaster Part Question

[TreeSlayer]

i ordered an OC44 transistor from Small Bear and this is what i received. i went to the Geofex site and could only find something on their version, The Dallas Rangemaster. my question is, what are the resistors for, and how do i orient the CV7003?

[midwayfair]

Use a socket. Typically with the writing facing you, it will be C-B-E, but not always. If yours is black glass, the red dot is the collector, but they have two gains.

That part number is also an OC44, just a later manufacturing date.

[TreeSlayer]

Use a socket. Typically with the writing facing you, it will be C-B-E, but not always. If yours is black glass, the red dot is the collector, but they have two gains.

That part number is also an OC44, just a later manufacturing date.

i took a pic, and forgot to put it on... 

[Haberdasher]

smallbear gain tests all their germanium transistors I think, and they include the correct resistors to use in the circuit instead of the stock values so it will bias correctly without you having to figure it out on your own.

as far as the orientation, I'm not sure.  the cv's usually have a red dot on them so that will probably be your collector, and the offset one in the middle is your base.  so that makes the other one the emitter.  Or just socket it try it different ways until it sounds the best

[TreeSlayer]

smallbear gain tests all their germanium transistors I think, and they include the correct resistors to use in the circuit instead of the stock values so it will bias correctly without you having to figure it out on your own.

as far as the orientation, I'm not sure.  the cv's usually have a red dot on them so that will probably be your collector, and the offset one in the middle is your base.  so that makes the other one the emitter.  Or just socket it try it different ways until it sounds the best

ok, i think i understand. what do you mean by "socketing" it?

[Haberdasher]

well you probably know the good germanium trannies like you bought are no longer made and are becoming more and more rare as time goes by.  so most of us leave the leads on the tranny pretty long, and solder a socket into the pcb. inserting the transistor into this socket allows it to be easily rotated if you have it in wrong, or pulled out later to possibly use it in something else down the road.  and there's no chance of damaging the part during installation or removal from the soldering iron heat.

Here's a couple of links the particular type of socket I mean
http://www.smallbearelec.com/servlet/Detail?no=147
http://www.mammothelectronics.com/TO-18-Package-Round-Transistor-Socket-p/620-to18.htm

[TreeSlayer]

well you probably know the good germanium trannies like you bought are no longer made and are becoming more and more rare as time goes by.  so most of us leave the leads on the tranny pretty long, and solder a socket into the pcb. inserting the transistor into this socket allows it to be easily rotated if you have it in wrong, or pulled out later to possibly use it in something else down the road.  and there's no chance of damaging the part during installation or removal from the soldering iron heat.

Here's a couple of links the particular type of socket I mean
http://www.smallbearelec.com/servlet/Detail?no=147
http://www.mammothelectronics.com/TO-18-Package-Round-Transistor-Socket-p/620-to18.htm

ok, i gotcha! so really, the resistors that came with it are irrevevant to what i'm doing?

[Stomptown]

well you probably know the good germanium trannies like you bought are no longer made and are becoming more and more rare as time goes by.  so most of us leave the leads on the tranny pretty long, and solder a socket into the pcb. inserting the transistor into this socket allows it to be easily rotated if you have it in wrong, or pulled out later to possibly use it in something else down the road.  and there's no chance of damaging the part during installation or removal from the soldering iron heat.

Here's a couple of links the particular type of socket I mean
http://www.smallbearelec.com/servlet/Detail?no=147
http://www.mammothelectronics.com/TO-18-Package-Round-Transistor-Socket-p/620-to18.htm

ok, i gotcha! so really, the resistors that came with it are irrevevant to what i'm doing?

I would personally use those resistors in place of the stock values listed in build doc for R3 and R5. It looks like the packaging specifies that resistors were specifically chosen for that transistor in a Rangemaster build.

[Haberdasher]

right, so for the rangemaster I think you would use the 43k for r1 and the other for r2, and that would get your germanium transistor biased to -6.6v or whatever it says on the smallbear package.  and that is presumably the optimum voltage for the best transistor sound in this circuit.

[TreeSlayer]

right, so for the rangemaster I think you would use the 43k for r1 and the other for r2, and that would get your germanium transistor biased to -6.6v or whatever it says on the smallbear package.  and that is presumably the optimum voltage for the best transistor sound in this circuit.

thanks, guys. that makes sense to me.

[TreeSlayer]

i have rangemaster built and tried to rock it, but you have to turn the boost up a third to get any sound, and all the way up to get decent volume, and it's actually a tad louder without it. i used 43k in R1 and a 3k in R2. i also don't get any voltage to the transistor. the sound does change when you turnT/M switch off and on.

[Stomptown]

The advice to insert the resistors in R1 and R2 was based on the assumption that you were using a Madbean Rangemaster PCB. Can you confirm that you are using the Madbean board? If not you will need to find the schematic for your board and compare it to this schematic found on the Small Bear site to figure out where the 2 resistors go:

https://www.smallbearelec.com/Projects/Rangemas/Rangemas.html

[TreeSlayer]

The advice to insert the resistors in R1 and R2 was based on the assumption that you were using a Madbean Rangemaster PCB. Can you confirm that you are using the Madbean board? If not you will need to find the schematic for your board and compare it to this schematic found on the Small Bear site to figure out where the 2 resistors go:

https://www.smallbearelec.com/Projects/Rangemas/Rangemas.html

yes, i am using a madbean PCB. are there any others? ;{D

[JakeFuzz]

Hmm, my very first guess would be to double check the transistor orientation. The way old alloy junction BJT's are made there is a possibility that they work backwards (mixing up the collector and the emitter) but with altered properties like lowered gain. Can you confirm that the red dot on the side of the transistor casing is not at the socket point with the tab. The tab on the socket indicates the emitter and the red dot on the casing denotes the collector.

Other than that I would say voltage readings at all of the transistor leads would be the way to move forward.

[Stomptown]

yes, i am using a madbean PCB. are there any others? ;{D

I think tonepad has one - or at least they used to. I just wanted to make sure cause it wasn't clear in the posts above. It sounds like you are fine with the small bear resistors in r1 and r2 then...