negative supply

[t.man]

hi,
They are 220µF at 16Vwkg[min] Electrolytic and a 0.05µF ceramic, a 0.047µF would be OK.

Any of the 1N400x diodes will be OK.

hi eric,

i couldn't find either 0.05uF or 0.047uF. only 0.01.
but i'm waiting to hear if they can't get one. til then any replacement for the time being?

 

[ericgibbs]

hi eric,

i couldn't find either 0.05uF or 0.047uF. only 0.01.
but i'm waiting to hear if they can't get one. til then any replacement for the time being?

hi,
You could increase the values of the two resistors, say by times 5, until the 0.047uF is available.
Use the formula inthe datasheet to work out the exact frequency

 

[Hero999]

Is there any reason why you can't use a 12VAC adaptor?

The circuit would be far simpler.

 

[t.man]

hi,
You could increase the values of the two resistors, say by times 5, until the 0.047uF is available.
Use the formula inthe datasheet to work out the exact frequency

from the formula in the datasheet(astable operation): using the values as they are with 0.05uF i get f = 3.3111...khz
for 1.2K x 5 = 6K and 3.9K x 5 = 19.5K i also get something similer which is 3.3111...khz

would i find 19.5K or i have to make serial connection of 3.9K's?

 

[ericgibbs]

from the formula in the datasheet(astable operation): using the values as they are with 0.05uF i get f = 3.3111...khz
for 1.2K x 5 = 6K and 3.9K x 5 = 19.5K i also get something similer which is 3.3111...khz

would i find 19.5K or i have to make serial connection of 3.9K's?

hi,
I would try a 18K or 22K the timing isnt critical.

For the other resistor a 5K6 or 6K8

 

[t.man]

hi,
I would try a 18K or 22K the timing isnt critical.

For the other resistor a 5K6 or 6K8

i was mistaken about the 0.01uF cap. they don't have one. they only have the pico and nano ranges.
i can try hero999 idea, but i only have Vdc supply only. can i use it?

 

[ericgibbs]

i was mistaken about the 0.01uF cap. they don't have one. they only have the pico and nano ranges.
i can try hero999 idea, but i only have Vdc supply only. can i use it?

hi t,
Not in the way 'hero' has suggested, his idea is based on half wave rectifiers.

How much -V current are you needing.?

EDIT: whats the -V for.?

 

[Hero999]

i was mistaken about the 0.01uF cap. they don't have one. they only have the pico and nano ranges.
i can try hero999 idea, but i only have Vdc supply only. can i use it?

I thought you wanted to use a mains adaptor?

They make them with an AC output too.
**broken link removed**

from the formula in the datasheet(astable operation): using the values as they are with 0.05uF i get f = 3.3111...khz
for 1.2K x 5 = 6K and 3.9K x 5 = 19.5K i also get something similer which is 3.3111...khz

would i find 19.5K or i have to make serial connection of 3.9K's?

Did you know that resistors only normally come in a standard range of preferred values?
https://en.wikipedia.org/wiki/Preferred_numbers#Capacitors_and_resistors

For resistors, it's normally fine to just use the nearest E24 value, in fact most of the time even the nearest E12 value will do.

Most types of capacitors are only made in E6 values so just choose the nearest one, most of the time the nearest E3 value (not in the Wikipeda article but the E3 series is 10, 22 and 47) will do.

In this application frequency isn't important so just pick the nearest E6 resistor and capacitor values.

Another option is to use a virtual earth circuit which might be even better if you have a spare op-amp on the IC or you could use a quad op-amp.

 

[t.man]

hi t,
Not in the way 'hero' has suggested, his idea is based on half wave rectifiers.

How much -V current are you needing.?

EDIT: whats the -V for.?

hi,

i've got 0.01 finally with 22K and 6.8K/ 5.62k so i'm gonna try the configuration now.