madbeanpedals::forum

Projects => General Questions => Topic started by: garfo on September 16, 2024, 06:44:26 AM

Title: SMD version of MPSA18
Post by: garfo on September 16, 2024, 06:44:26 AM
I have been looking for an SMD package for the MPSA18 and I cannot find anything. Has anyone had any luck with finding this as an smd package?
Title: Re: SMD version of MPSA18
Post by: jwin615 on September 16, 2024, 01:43:46 PM
Could use mmbt22222
Title: Re: SMD version of MPSA18
Post by: garfo on September 21, 2024, 06:26:38 AM
that transistor does not have the same characteristics that I need to replace the MPSA18. I need the higher voltage handling capability, Lower noise figures and also higher gain specs. This is for a Push-pull gain stage to reduce Harmonic distortion.
Title: Re: SMD version of MPSA18
Post by: mauman on September 21, 2024, 08:12:06 PM
I did a search at Mouser for SMD BJT that meet or exceed all the relevant properties of the MPSA18, and they have 47 choices.  Here is the link to search results.  The noise factor and beta are not searchable properties, so you'll have to sort those qualities for yourself, but this should give you a head start.  Once you identify the part number you need, Mouser has a presence in Portugal, pt.mouser.com.   
 
https://www.mouser.com/c/semiconductors/discrete-semiconductors/transistors/bipolar-transistors-bjt/?collector-%20base%20voltage%20vcbo=45%20V~~-&collector-%20emitter%20voltage%20vceo%20max=45%20V~~-&collector-emitter%20saturation%20voltage=200%20mV~~-&configuration=Single&emitter-%20base%20voltage%20vebo=6.5%20V~~-&gain%20bandwidth%20product%20ft=160%20MHz~~-&maximum%20dc%20collector%20current=200%20mA~~-&mounting%20style=SMD%2FSMT&pd%20-%20power%20dissipation=625%20mW~~-&product%20type=BJTs%20-%20Bipolar%20Transistors&transistor%20polarity=NPN&rp=semiconductors%2Fdiscrete-semiconductors%2Ftransistors%2Fbipolar-transistors-bjt%7C~Maximum%20DC%20Collector%20Current%7C~Collector-%20Emitter%20Voltage%20VCEO%20Max%7C~Collector-%20Base%20Voltage%20VCBO%7C~Emitter-%20Base%20Voltage%20VEBO%7C~Collector-Emitter%20Saturation%20Voltage%7C~Pd%20-%20Power%20Dissipation%7C~Gain%20Bandwidth%20Product%20fT
Title: Re: SMD version of MPSA18
Post by: jwin615 on September 21, 2024, 10:55:50 PM
Don't you need a matched PNP NPN pair for(optimal) push pull? May look at transistor arrays if that's the case.
I assumed this was for a pedal so didn't take voltage into account...

I'll add, check out the Alfa offerings
Title: Re: SMD version of MPSA18
Post by: garfo on October 07, 2024, 10:55:52 AM
Thank you. I will have a look into this.
Quote from: mauman on September 21, 2024, 08:12:06 PMI did a search at Mouser for SMD BJT that meet or exceed all the relevant properties of the MPSA18, and they have 47 choices.  Here is the link to search results.  The noise factor and beta are not searchable properties, so you'll have to sort those qualities for yourself, but this should give you a head start.  Once you identify the part number you need, Mouser has a presence in Portugal, pt.mouser.com.   
 
https://www.mouser.com/c/semiconductors/discrete-semiconductors/transistors/bipolar-transistors-bjt/?collector-%20base%20voltage%20vcbo=45%20V~~-&collector-%20emitter%20voltage%20vceo%20max=45%20V~~-&collector-emitter%20saturation%20voltage=200%20mV~~-&configuration=Single&emitter-%20base%20voltage%20vebo=6.5%20V~~-&gain%20bandwidth%20product%20ft=160%20MHz~~-&maximum%20dc%20collector%20current=200%20mA~~-&mounting%20style=SMD%2FSMT&pd%20-%20power%20dissipation=625%20mW~~-&product%20type=BJTs%20-%20Bipolar%20Transistors&transistor%20polarity=NPN&rp=semiconductors%2Fdiscrete-semiconductors%2Ftransistors%2Fbipolar-transistors-bjt%7C~Maximum%20DC%20Collector%20Current%7C~Collector-%20Emitter%20Voltage%20VCEO%20Max%7C~Collector-%20Base%20Voltage%20VCBO%7C~Emitter-%20Base%20Voltage%20VEBO%7C~Collector-Emitter%20Saturation%20Voltage%7C~Pd%20-%20Power%20Dissipation%7C~Gain%20Bandwidth%20Product%20fT
Title: Re: SMD version of MPSA18
Post by: garfo on October 07, 2024, 10:56:33 AM
Quote from: jwin615 on September 21, 2024, 10:55:50 PMDon't you need a matched PNP NPN pair for(optimal) push pull? May look at transistor arrays if that's the case.
I assumed this was for a pedal so didn't take voltage into account...

I'll add, check out the Alfa offerings
For this particular circuit, not really.