Transformer less power supply

[thomasPlam]

hi all
am working with a timer triggered device using pic 16f876a. for that am planing to give a transformer less power supply. i don't have much experience in that. If their any major problem can occur due to that. please help me ,i will be thankful for your valuable opinions.

regards
thomasplam

 

[mneary]

Other than electrocution and fire, no problems.

 

[Hero999]

Sorry but it's one of those things that if you need to ask you shouldn't be doing it.

A transformerless power supply is not isolated from the mains so your entire circuit poses a potential shock risk.

If the whole circuit is encased in an insulating enclosure and no parts of the circuit are connected to any other circuits, the shock risk can be mitigated but it needs careful design which requires experience.

 

[3lectrokid]

have a look here. it will save you from electrocution and may provide isolation from the mains. however i do not know if it has so i would contact rapid and see what they say.

Edit: sorry i forgot to put the link in : **broken link removed**

 

[KMoffett]

thomasplam,

What advantage are looking for with a transformerless AC/DC power supply?...size?...cost? How much current will your circuit need at 5V(?)? I pick up very small 5.0VDC/700mA regulated cellphone chargers for $0.39USD at thrift stores. If it needs to provide 5VDC inside an existing AC powered device, you can carefully remove the charger case and deal with just the SMPS PCB.

Ken

 

[HiTech]

39¢ for a SMPS 5vDC, 700ma supply? Wow, that's less than dirt cheap! What name thrift store are these available at?

 

[KMoffett]

It was Value Village, a thrift store sponsored by ARC in Edina, Minnesota. Most often $0.99. Goodwill and Savers want ~$3.99 for the same thing. Even at $4, they're still cheap for a very small, regulated line power supply for µC projects.

Ken

 

[thomasPlam]

thomasplam,

What advantage are looking for with a transformerless AC/DC power supply?...size?...cost? How much current will your circuit need at 5V(?)? I pick up very small 5.0VDC/700mA regulated cellphone chargers for $0.39USD at thrift stores. If it needs to provide 5VDC inside an existing AC powered device, you can carefully remove the charger case and deal with just the SMPS PCB.

Ken

hi ken,
obviously cost and size . i got ckt and it will cost me less than 0.22$ . my need is 5v 25mah.. only... plz reply. thank you very much.

regards & thanks
thomasplam

 

[mneary]

25 milliamp hours? Why not a tiny battery? How much current?

 

[thomasPlam]

25 milliamp hours? Why not a tiny battery? How much current?

hi,
its only Milli amp, actually its for a 230v triggering device,want to drive a mcu...

regards & thanks
thomasplam

 

[Hero999]

hi ken,
obviously cost and size . i got ckt and it will cost me less than 0.22$ .

In what quantity?

You'll do well to buy all the components for that price unless you order in large volumes from China.

 

[schmitt trigger]

hi all
am working with a timer triggered device using pic 16f876a. for that am planing to give a transformer less power supply. i don't have much experience in that. If their any major problem can occur due to that. please help me ,i will be thankful for your valuable opinions.

regards
thomasplam

If you are actually planning to produce and sell this device, it will require safety agency recognition, which is quite elaborate to obtain. That is one of the main reasons for using wall-wart plug packs, as even large companies don't want to mess with that.

 

[thomasPlam]

If you are actually planning to produce and sell this device, it will require safety agency recognition, which is quite elaborate to obtain. That is one of the main reasons for using wall-wart plug packs, as even large companies don't want to mess with that.

hi
yes you are right i want to sell it. nd what that safety stuff.

regards
thomasplam

 

[blueroomelectronics]

hi
yes you are right i want to sell it. nd what that safety stuff.

You need to get it electrically approved in whatever countries you plan to sell it in. It's an expensive process and will probably not be allowed for sale in many countries. If it electrocutes somebody they will sue the ass of you.

Just resell the approved Chinese version, try to get one that is electrically approved for the country you're reselling it in.

 

[thomasPlam]

You need to get it electrically approved in whatever countries you plan to sell it in. It's an expensive process and will probably not be allowed for sale in many countries. If it electrocutes somebody they will sue the ass of you.

Just resell the approved Chinese version, try to get one that is electrically approved for the country you're reselling it in.

hello,
thanks for the information man.
regards
thomasplam

 

[shokjok]

Let's hope that you don't have criminal intent for this project. You don't mention your electronics background, or possession of any diplomas or degrees. What do you intend to activate with this circuit - a rod missile? Homeland Security will quickly detain you.

 

[blueroomelectronics]

Let's hope that you don't have criminal intent for this project. You don't mention your electronics background, or possession of any diplomas or degrees. What do you intend to activate with this circuit - a rod missile? Homeland Security will quickly detain you.

Huh? Where did that come from?

 

[thomasPlam]

Let's hope that you don't have criminal intent for this project. You don't mention your electronics background, or possession of any diplomas or degrees. What do you intend to activate with this circuit - a rod missile? Homeland Security will quickly detain you.

dear shokjok,
I dont have any criminal intend behind this, i have a masters in embedded system. its just bcz of curiosity....

Regards
Thomasplam

 

[Hero999]

No one's accusing you of being a criminal.

Why? Is there a reason we should be worried about that?