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#### ET200

##### New Member
hi everybody
i have problem with knowing this diode (in attached, D5). what kind of diodes? schottky? printed code in its body is j 8j i cant understand this.it used in power supply 110 v ac to DC(measured 150 v dc) for energize an air circuit breaker. this diode use inverse in output to damp spike voltage that create when voltage will be falling (off breaker command). now this diode was damage and i want to replace with another diode.now i can't identify this diode for find same type. i don't have schematic. sorry for my Sentences, English is not my first language.

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#### audioguru

##### Well-Known Member
It is a high voltage silicon power diode. A Schottky diode is for low voltages.
A 1N4007 is available everywhere and is rated for 1000V. Its max allowed current is 30A for 8.3ms.

#### ET200

##### New Member
how i can understand specific parameters for this diode? 30A @ 8.3 ms for 1n4007, but what about my damaged diode?

Try the 1n4007

#### AnalogKid

##### Well-Known Member
Without the original part number, you never will know the exact specs of the original diode. But the nature of the application lets us make some reasonable assumptions and recommend a contemporary part that almost certainly will work. The 1N4000 series of diodes is very common in circuits such as yours. It is rated for 1 A continuous RMS or DC current, at voltages from 50 to 1000 V. The capacitors on board are rated for 350 V, and it always is a good idea to use diodes that are rated for at least twice the circuit voltage. Since you haven't posted the schematic, we assume the peak circuit voltage is 350 V. A 1000 V 1N4007 should do well.

ak

#### Colin

##### Active Member
Why are you talking about a 1,000v diode when the voltage is 150v ? A 400v diode for 0.9 cents is all that is needed.

#### picbits

##### Well-Known Member
Why are you talking about a 1,000v diode when the voltage is 150v ? A 400v diode for 0.9 cents is all that is needed.
What is the part number of that diode and where can the OP get it easily for 0.9 cents ? I pay around £0.01 for a 1N4007 and they are readily available almost anywhere in the UK.

#### Colin

Brand New
• $0.99 • Free international shipping You only specify 1,000v diode for a REASON. If the voltage is just 150v you specify 400v. It doesn't matter that the cost is the same, it just shows intelligent engineering. I have had this argument with two magazines that don't have any technical staff. They have never replied. #### GromTag ##### Active Member Hmm, looks to be a Philips design, tho without the numbers, the exact part is not too probable. Those are for switching but tend to have a low forward drop by design. Typical 500mv. Far as I can gesture. #### picbits ##### Well-Known Member Brand New •$0.99
• Free international shipping

You only specify 1,000v diode for a REASON.

If the voltage is just 150v you specify 400v. It doesn't matter that the cost is the same, it just shows intelligent engineering.

I have had this argument with two magazines that don't have any technical staff.
They have never replied.
As far as I read it, this is a diode to clamp the reverse coil voltage when the solenoid is powered off.

The 1000V diodes are exactly the same price as the 400v ones from eBay

https://www.ebay.com/itm/100PCS-1A-...130209?hash=item2a56ef0061:g:WosAAMXQ4uJR9nXU

Any reason not to use the higher voltage rated ones in case the coil collapse voltage is higher than 400v ?

#### kubeek

##### Well-Known Member
Any reason not to use the higher voltage rated ones in case the coil collapse voltage is higher than 400v ?
The coil collapse voltage is never higher than 0.7V, since that is what the diode is there for, to clamp it. The voltage rating for the diode depends solely on the power supply voltage of the relay coil.

#### Colin

##### Active Member
As I said before, you have to give a REASON . . . a specific reason . . . why a high voltage or high current or fast-acting, diode is required.
That's why I specify 1N4004 as it is a general purpose diode and requires no thinking. It is silly to specify 1N4001 (50v) or 1N4002 as this will require stocking a wide range of un-necessary components.
The same with transistors. BC547 indicates the weakest, poorest, simplest, non-critical transistor and infers ANY transistor will do. It is the worst transistor ever invented and how Philips got away with such rubbish I will never know.

#### audioguru

##### Well-Known Member
I specified using a 1N4007 genuine rectifier diode because it is available everywhere but a 1N4004 is not.
He needs one good diode, not 100 cheeeep counterfeit fakes from ebay.

#### be80be

##### Well-Known Member
I could send him one just like it out of a power supply it's good but I don't no if it's rated for 400 volts it was on the line side. I'm guessing 250 maybe more.
Id go the 1N4007 Im with audioguru there every where and easy to find in old gunk laying around.

#### Ian Rogers

##### User Extraordinaire
Forum Supporter
I can't believe this thread..... I got 1000 high quality 1n4004's last week for £6... Who gives a monkeys... How much and where... If the man can get a single diode fine... Why would he need 100 of the things...

Just go with audioguru and picbits...

#### RichTheDude

##### Active Member
I fail to see why for hobbyist and or development applications you would ever bother to stock and use a 1N4004 over a 1N4007 in your laboratory. In the UK, the 1n4004 is typically slightly more expensive than the 1n4007 (try Rapid for example), so the rationale to use an 1n4004 is moot.

#### chemelec

##### Well-Known Member
UF is Ultra Fast.

#### ET200

##### New Member
thank u every one, i found similar type diode its ultra-fast avalanche sinterglass diode , i can't replace 1n4007 because : 1-Vr=1.6 kv 2-Trr=75ns VS 1kv and 8.3 ms in 1n4007
my reverse voltage is 150 vdc (not 350 v) but Trr is important.my forward voltage depended di/dt. i think UF4007 is my ideal. Though i can't understand what means green in Cathode
sign?

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