Dr Ronald Stiffler SEC technology

[erfandl]

Hi Erfandl,
If you wish to use also a pnp type replacement,  then out of the many types there is the 2N3906 which may be available for you. These are the data sheets for it, many manufacturers produce it:
http://www.datasheetcatalog.com/datasheets_pdf/2/N/3/9/2N3906.shtml  If you have  RS Components, Mouser, Digikey, Futurlec or similar vendors, then I can look up some more types for you from the available offers. The PN4248 is a general purpose, low noise audio transistor, the latter feature is not needed here. There are two parameters that need attention for a substitute type: low saturation collector-emitter voltage and a decent h_FE of 100 or higher and perhaps you can find such locally.

Gyula

thanks Gyula I found 2N3906 in my area 

[Slider2732]

2N3906's are decent workhorses for PNP.
2SA733 are good and plentiful too.


The seller, HiLetgo, got back to me saying they are sorry.
Also to recontact if there is still a problem (?)
Does anyone know how to re-contact sellers on Amazon ?
Update - found a way to contact and have done so.

[itsu]

Slider,

see bottom of this page:   http://www.hiletgo.com/

Itsu

[Slider2732]

Many thanks Itsu,
It should be ok from now, i've just luckily not had to do the runaround emails thing before on Amazon. They seem fine, but understandably guarded about fake claims.

[mikrovolt]

When Doctor Stiffler said  "What does mass have to do with it ? "
He was dealing with less experienced persons doing the series resonance experiment.
He meant that the experimenters should use a large plate capacitor (aluminum blocks)
instead of the small pico farad component. Increase of surface area.

The tiny signal generator boards are the same it is difficult to remove the vhf zig zag.
One board kk moon MHS 5200A was big enough to get in and remove the noise. Distributor=Hiletgo.
Also upgrading the final op amp brought the SG to a descent quality. The reinvented wheel.
Increase the surface area, in this case with a congested board. Cut the trace and mount modification up.
Requires precision skill, a microsope and steady hand. The lightning on the sine wave is another example how great engineers where replaced by digital dummkopfs that don't listen. Lacking the precision methods. handicapping the world with oneness.
The MHS 5200  https://youtu.be/-xOKNi8M3xE