Nope. After the rectifier there must be a pretty big filter capacitor that charges to the peak voltage minus a couple of rectifier volts (+71.5V).I have a 52V transformer that after rect. produces 3.3A at 52V.
Honestly the Internet can be a nest of worms, there are many circuits that don't use a resistor at all.
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I have a 52V transformer that after rect. produces 3.3A at 52V.
Nope. After the rectifier there must be a pretty big filter capacitor that charges to the peak voltage minus a couple of rectifier volts (+71.5V).
Yes.Can I edit my profile ?
As has already been said, a bridge rectifier and reservoir capacitor will produce (52V *1.414) -(2 * 1V) = 71.5V across any value reservoir capacitor (in practice over around 1nF) with no current drain from the reservoir capacitor.I have a 52V transformer that after rect. produces 3.3A at 52V.
10,000uF is an excellent value reservoir capacitor for your work- you made a good choice. 3V peak to peak ripple voltage across a reservoir capacitor is perfectly normal. A little later down the line you can use another simple formula to derive the ripple current that the capacitor is passing to ensure you do not exceed the ripple current rating of your 10,000uF capacitor. By the way treat reservoir capacitors, batteries etc with care. Never get your face into a position where your eyes can be damaged by an explosion.I thought 10,000uF would cover most things. Mind you at 3A 3V is quite a bit. If I double the cap to 20,000uF that would halve the ripple.
Bangood are a great company and very popular with some of the ETO men. Chinese girls have two names: Chines and western. Ruth will be her western name.I looked on Amazon for a buck convertor with an input of 60V. I ended up at Banggood - China. There delivery times are rather slow, I think some of my stuff is still on a bullock cart stuck in a paddy field. My contact at Banggood is Ruth - strange Chinese name. She's very polite and keeps me well informed.
They sell 'all sorts' of strange items on Banggood - usually pink.
Banggood - maybe they started out as a house of ill repute or a good sense of humour. . Bit late for me, I'm 70 - unless they have paramedics on site.
I would only buy power transistors and big capacitors from a reliable source, which can be from the far east. Your 10,000uF capacitor will be plenty big enough, as already said.It's a good site to browse, the electronic stuff is so cheap. Indecently they are making fake 2N3055's that blow at 1A 30V. That's on Youtube. I got mine from CPC, Probably Chinese. I expect my capacitor is made from kitchen foil. Good comments though. They do a 22,000uF for the same price £2.75. I was worried about the 'inrush' thing. Sorry to be so technical.
I buy a bit of stuff from the far east, mainly ebay and Alibaba and the prices are amazing, like £0.99UK for some items, including postage and packing from Hong Kong. Delivery is typically 5 weeks. But there are UK based sellers, which are slightly more expensive, but deliver in two days.I found this and I have ordered it along with other bits, some of which have arrived :-
**broken link removed**
It's less than the price of 2 packets of fags (I vape now) so fingers crossed. I wanted to build my own V regulator though, buck regulators are somewhere in the future so I thought I would build a linear room warmer.
Yes, the small size of switch mode power supplies is amazing, but when you investigate them you will see that the reason is quite straight forward. Very roughly speaking the size of a power supply is inversely proportional to conversion frequency. Your linear power supply frequency is 50Hz and switch mode power supplies can have a conversion frequency as high as 4MHz, so you can get an idea how it is done.One of my daughters bought me a battery for vaping. It can go up to 80W with variable V and A and temp control. It has a small LCD screen that shows Watts, Volts, Coil resistance and Amps but it can be changed to show other parameters. It has a battery status bar. It's about half the size of a cigarette packet. I use 7W, it's more than enough. I imagine it has a buck convertor but how on earth do they get it down to this size is beyond me.
Hi Colin,For a current of 4 amps, you only need one 2N3055 and using two or more will have absolutely no advantages.
You can even use the plastic version for 40 cents.
It is always prudent to be aware of danger especially to the eyes. Blowing up electrostatics is great fun. When our lab instructor wasn't looking we used to plug an electrolytic in the mains- what a mess.I deliberately popped a 16V small cap not much bigger than a fag end and it made quite a crack. The bottom opened up like a flower. Elli our dog ran out the room and she's OK with thunder. When I first fire up the 10,000uF don't worry I'll be well away from it. Normally it will be running under the steel cover but maybe I'll add a bit of temporary protection around it while I'm messing about. I guess a drain resistor might be advisable as well.
Chinese girls are very pleasant. That is their objective. The result is that they do not recognize/resolve problems. We have got to know a few oriental girls (and chaps) from the local Chinky restaurants and take sways. I would not send an Xmas card to Ruth or you may get a visit from a guy with a red band around his head wielding an axe.Ruth has become quite chatty. I expect they get a bit bored and she is very polite. It's me saying to her please don't worry I'll be patient. One never knows the circumstances so what's the point in getting angry, even if they get out of stock and the substitute is also out of stock. Poor girl seemed really worried. She keeps saying 'Please be patient'. I wonder what would happen if I sent her a Christmas card ?.
Handy little PSU- I know it well, in theory that is.I bought 3 x 1.25V to 38V 5A buck converters that all 3 fit into your fist. £3.80 all 3. Mind you they state a little heat sink and fan should be added for the 5A. I'll have to saw an old one up, I have a few small ones from PC power supplies. I could fit all 3 under a 40mm fan.
Just like with linear power supplies, there are some simple formulae that allow you to work out what is going on with switch mode power supplies.Yes, I read somewhere about the higher the frequency the smaller they get but despite estimating the size in ones mind when you actually hold one it's quite a shock.
Sounds like a good idea.The battery still has to provide the power though. Mind you I would estimate the total run time is only a few minutes till it needs recharging. That's two days vaping. I wonder if a drop of whiskey instead of the glycerine. straight into the blood stream.
That is good to know. I have never bought any cheap LEDS suspecting that they might be inferior.The 100Pcs of coloured 20mA 5mm LED's I got are superb. Many UK job lots don't include white and blue and they cost a lot more than £1.72
thanks, will have a look.Might I suggest you have a look at bigclivedotcom on Youtube. He's an LED (warm white) real lead solder fanatic. He was in charge of The Royal Edinburgh Military Tattoo electronics. He likes Poundland LED bits.
OuchI once had 410V DC across my nose - enough said.
Here is a reply to the above extractHi Colin. It's so nice to know there is someone else making the same mistakes as me.
And another reply to another extractDo you know my friend Irena, lives just outside Sydney ? Perhaps you don't.
Yes, you can do that quite simply. In fact, it is normal procedure in power supplies to reduce the dissipation in the output transistor as you say. A suitable circuit is shown below.... this transformer I have is 18VAC x 4.44A + 18VAC at 4.44A therefore I think centre tapped ?
I had it wired for 18VAC at 8.88A. I did check I could with CPC Farnell first. I then decided on 36VAC at 4.44A.
Is it possible to switch between 26V DC x 3.3A and 52 DC x 3.3A. I don't think I see a problem with the switching arrangement at the output from the transformer. Would everything that follows on work ? If you halve the difference in Volts between Input and load then you would halve the Watts on the 2N3055's - and heat ?
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