Recently I discovered a very interesting youtuber and phonetician Dr. Geoff Lindsey. If you are interested in English phonetics, I highly recommend subscribing to his channel.
In his video “Schwa is never stressed” – FALSE he talks about the schwa /ə/ sound. His suggests that in American English it should be the only phoneme for both unstressed sound /ə/ and stressed sound /ʌ/.
And indeed several respectable dictionaries, such as Merriam-Webster’s Collegiate Dictionary or The Routledge Dictionary of Pronunciation for Current English, use the symbol /ə/ for both stressed and unstressed sounds.
So now there’s an option in our English phonetic translator that allows you to choose how stressed schwa /ə/ will be displayed in American English.