Replacement components?

teamgardner · 21, May, 2012 - 21:30:49

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.

radiomarty · 21, May, 2012 - 22:12:59

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

teamgardner · 21, May, 2012 - 22:44:57

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

radiomarty · 21, May, 2012 - 22:46:24

Search them on e-bay - always available on there - Marty

teamgardner · 21, May, 2012 - 22:51:17

Thats where I've been looking. I just tried and still cant get anything. I'm searching for fst290

marra · 21, May, 2012 - 22:53:45

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

radiomarty · 21, May, 2012 - 23:00:49

OPPS - JUST REALISED YOUR TALKING ABOUT THE POD NOT CONTROL BOX DOOOOOOOOOOOOOOOOOOOH

teamgardner · 21, May, 2012 - 23:04:20

You had me worried there. I thought I was going daft.

radiomarty · 21, May, 2012 - 23:06:21

In that case i think they are suitable thanks for sharing them and sorry about my senior moment - i need some sleep !!!!!

KarlG · 24, September, 2012 - 22:52:03

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.

teamgardner · 27, September, 2012 - 12:14:08

thanks Karl. I have had no problems with the pod but if i do get problems now i will know why.

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Replacement components?

marra