Transistor equivalent

Looking for a darlington transistor substitute used in Telefunken reel to reel audio output, rated at 20 watts. It’s a BD598. Any help appreciated. Model of recorder is Telefunken.

Hi, I think the alternative is 2SA1135 pnp. Thank you.

I have a program for alternatives

Hello John482 and welcome to the DigiKey TechForum.
As some other options that may work based on this information I could find about BD598.
You can look at D45H11GOS-ND and D45VH10GOS-ND, that may work as alternatives for you.

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Hi, I need help. How do I upload a photo to the forum?

Adding to @nick_13812’s response, these transistors typically work as complementary PNP-NPN pairs, and as such, one should replace transistors in pairs to retain symmetry in characteristics.

Therefore, if one selects the PNP D45H11GOS-ND, the D44H11G would be the complementary NPN transistor to use with it.

Note that these are not drop-in replacements with identical characteristics to the BD598. Both physical and electrical specs differ, but these seem to be some of the most similar transistor pairs we currently stock.

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So these are very near spec for the bd598 and bd597? Darlington I assume? What company do you represent? I ordered some parts from Littlediode.com and now I hear they are selling fakes!

We are DigiKey Electronics. We are an franchised distributor. Please check out the home page:

You can scroll to the bottom in the black. The first item under information is about Digikey.

I understand they aren’t exact drop in replacements, but it would be great if they didn’t blow other components on the power output board. Thanks.

Hi john482,

No guarantees on anything here. These are merely possible suggestions, based on my experience. It’s up to you to decide whether to try out the suggestions and to determine if any modifications to your circuit is necessary to accommodate any alternative parts.

My process was as follows: I found a datasheet here for the BD598, then filtered through our (DigiKey’s) stocking products, and based on my experience, selected the D45H11 and D44H11 as reasonably similar parts, based on same or better Vce, similar hfe, same or better current handling, and similar bandwidth.

By the way, based on the datasheet I found above for the BD598 (it’s conceivable that it is not a correct datasheet, as info for this part seems to be scarce), it does not appear to me that it is a Darlington type transistor. I could be wrong there, but the datasheet I found makes no mention of it being a Darlington device. Furthermore, the bandwidth spec is quite high, and the hfe , Vce(sat), and Vbe(on) specs are all quite low for a Darlington device. Thus, the parts I referenced are not Darlington transistors and seem to be fairly similar.

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