replacing rare electronic components

[ramy]

i can't find the 10 microfarad and 0.4 microfarad capacitor for these circuits:

http://www.circuitstoday.com/wp-content/uploads/2008/03/intruder-alarm-circuit-1.JPG

http://www.circuitstoday.com/wp-content/uploads/2008/04/fire-alarm-circuit.jpg

I need to know what can i replace them with?

 

[ramy]

and also the BC157 transistor

 

[Harald Kapp]

Try BC557 for the BC157.
10µF and 0.4µF are standard values. Any electronics distributor will sell you that. Instead of 0.4µF you can search for 400nF, that is the same capacitor.

BTW, do you mean 0.04µF as required by the second schematic? That would be 40nF. You can use 2*22nF in parallel instead without much of a difference to the circuit.

 

[(*steve*)]

0.4µF

Well, 0.047 is...

Even closer than two 0.022uF in parallel would be two 0.082uF in series.

Is it critical? (edit: probably not)

 

[brevor]

.039 uF is a close standard value.

 

[(*steve*)]

It is not unusual to find that E-6 values for capacitors are easier to obtain than the E-12 series.

Having said that, both 0.039 and 0.082 are in the E-12 and not the E-6 series.