T&L Publications

I came across a large LCD display which I thought would be nice in a digital alarm clock. I checked the internet for a digital clock chip with the proper LCD drives, but to my surprise, I could not find ANY. So I decided to the the PIC approach, but all the information I found are for serial LCD mod...

Hi folks, In face of the difficulties, I am accepting to increase the part count for this supply. I am thinking of using two regulators for each section, one configured as a current limiter and the other as a variable voltage regulator. The drawback is the value of the sensing resistor, wich is alwa...

First of all, thank you for your replies to this topic. Now, let me explain what I am trying to do a little further: In the IT-3121 the VCE voltage is obtained from the secondary of a transformer, after a half wave rectifiyng section (no capacitor). The amplitude is controlled by transistors arrange...

I consulted the National Semiconductor datasheet again just to make shure, but, as I thought, there is not an aplication like that in it.
I need to vary both the voltage and the current.
Do you have a different document?
Thanks

I need a circuit for a dual power supply where I could adjust the output from ~5 to 30V and limit the output current from ~100 mA to 1.5A. The circuit will be used as part of a transistor curve tracer I am trying to build, based on the old Heatkit IT-3121. I do not need lab quality regulation, but s...

Hi Edd,
Thank you for your reply.
I would like to see the more recent design that you have mentioned.
How will it possible?
Regards,
R.Oddone
P.S.
The URL of the schematics is:http://www.circuitarchive.co.uk/heath.htmweb page

I am trying to build an replica of the old Heathkit IT-3121 curve tracer. Altough most of the original semiconductor are obsolete, I could find replacement for them except for these two transistors. I have already spent a couple of hours in the internet searching all the resources I could find witho...