I have a 100 - 240v ac to 5v DC switching adapter. Is it possible to intercept the voltage just after the rectifier and get 120v dc. I have read different things, the consensus seems to be that switching adapters rectify 120vac to 120vdc then run it through a transformer to drop it to the needed voltage, then through some filtering and regulation. Is this correct?

I am trying to make a simple led light, if I use 120 vdc I would need less resistors. I believe.

 

Yes but no.

There is no practical or safe reason to do it.

In fact thread may well be closed for the suggestion.

 

when using the adapter on 120 volts ac in, there is about 170 volts after rectification and filtering. there is no 120 volts dc in there at all.

 

.... and that 170V is not mains-isolated so can be LETHAL.
Read the Terms of Service of this site regarding transformerless power supplies!

 

What type and number of LEDs do you have?

 

This thread is against the AAC forum rules, Chapter 6, as seen here:

6. Restricted topics. The following topics are regularly raised however are considered “off-topic” at all times and will results in Your thread being closed without question:

• Any kind of over-unity devices and systems
• Automotive modifications
• Devices designed to electrocute or shock another person
• LEDs to mains
• Phone jammers
• Rail guns and high-energy projectile devices
• Transformer-less power supplies

This can be found in our Terms of Service (ToS)