Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Can somebody explain the operation of this circuit, please?

Status
Not open for further replies.

Damo666

Member
Hi Guys,

This is the schematic of a Pye charger I recently received that's designed to charge 8.4V NiCad's.

What I want to know is; Do I get any indication when charging is complete? Is the bulb meant to extinguish?

If someone could explain how the circuit operates, I would be grateful.

Cheers,

Damian
 

Attachments

  • DSC04794.jpg
    DSC04794.jpg
    367.5 KB · Views: 113

dougy83

Well-Known Member
The bulb will extinguish when the current through the battery falls below ~2mA (that's 0.6V / 330 ohms)
 

Damo666

Member
Thanks for the reply.

Please can you explain how the circuit works, and also the purpose of the Zener Diode?
 

dougy83

Well-Known Member
)Please can you explain how the circuit works, and also the purpose of the Zener Diode?
The transformer converts the 240VAC to 27VAC. D1 rectifies this to 38VDC and C1 smooths the waveform somewhat. R3 and D2 regulate the voltage to 20V. R4 and R6 limit the current to the battery. The battery current passes through R5 and if the current is >~2mA, through TR1 Base-Emitter, which turns LP1 on brightly. If the current is <~2mA, TR1 will be pretty much off and LP1 will be dimmer (but possibly still glowing).
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top