Hi, I replaced some components with some alternatives. So far everything sees okay so I thought I'd put them up.
ZD1 in control box replaced by BZY88C24
TR1 & 2 In the pod replaced by BC557
I am not experienced with electronics so if anyone spots a problem with these can they let me know.
Off the top of my head bud without looking up the data sheets - the originals were a matched pair of NPN and PNP transistors therefore replacing them with the same for tr1 and tr2 wont work - you need the matched opposite of the BC557 ie AN BC547 thus giving you a matched PNP AND NPN pair - also need to check voltages and switching currents - PS I use the originals that are easily obtainable
Whoops! Glad you guys are here to help.
I couldnt find the originals anywhere. Do you you know where to get them from. I'd better swap them back
Search them on e-bay - always available on there - Marty :)
Thats where I've been looking. I just tried and still cant get anything. I'm searching for fst290
Quote from: radiomarty on 21, May, 2012 - 22:46:24
Search them on e-bay - always available on there - Marty :)
hi marty, could you give a link(s) please. thanks m
OPPS - JUST REALISED YOUR TALKING ABOUT THE POD NOT CONTROL BOX DOOOOOOOOOOOOOOOOOOOH
You had me worried there. I thought I was going daft.
In that case i think they are suitable thanks for sharing them and sorry about my senior moment - i need some sleep !!!!!
Hi teamgardner,
QuoteTR1 & 2 In the pod replaced by BC557
I recommend that you change 'BC557' to 'BC557C'. This is the transistor that Phil quoted.
The reason for this is the parameters for the 557 are not the same as a 557C.
The gain (hfe), or the amplification, are not the same. Check the following:
BC557 minimum gain is 125
BC557B " " " 220
BC557C " " " 420
In a worst case scenario you fit a 557 that has the min. gain you could end up with the system not working correctly.
Regards.
KarlG.
thanks Karl. I have had no problems with the pod but if i do get problems now i will know why.