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Pink Atom Module

Seger

New Member
Can you recommend where i can buy some 2 SD1071 that works? On the flywheel I just move the wedge track so I fix it! How do you measure if 2SD1071 is ok and with what type of test instrument, what values should you have? Feels like I'm close now!
 

debe

Active Member
Its a bit hard to see in the pictures, but the markings are the same on both transistors. But the one on the right is faulty, poor gain & will give intermitent spark or none at all.1.JPG2.JPG3.JPG
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
In one of the few threads, we discussed another possible substitute.

You can make a quick circuit to measure Hfe. You need a base resitor and a voltage source above 0.6V and a collector resistor to +V. Connect the emitter to ground. Right now, I'm too tired to look at the datasheet and suggest values.

You would measure the voltage across the collector resistor and convert to current i.e. Ic
Measure the voltage across the base resistor and determine Ib
Hfe = Ic/Ib

Those component testers and similar are really cheap as kits on www.banggood.com. Like less than $30.00 USD.
 

jeffsunnergr

New Member
Hi;
I have a MiniMac 130 chainsaw. I replaced the points with the Nova II. 1 hour of running and the Nova is done. I have burn up 3 Nova II trying to get the chainsaw running. I read the Nova II is an SCR unit. Is it true? I disassembled the Nova II but I can't find the specs for the semiconductor devices. The big semiconductor has on its package SMT2R8G another is C4 5C and the last is A4.
If I wanted to build a unit, which ATOM design should I use red, pink?
 

Skelle

New Member
Its a bit hard to see in the pictures, but the markings are the same on both transistors. But the one on the right is faulty, poor gain & will give intermitent spark or none at all.View attachment 119970View attachment 119971View attachment 119972
There's something strange here. The original darlington from a pink module returns an HFe of 17, and Uf (voltage forward) around 1 volt. Anyone tried to measure the original ATOM darlington? image.jpeg
 

Skelle

New Member
Besides that....not working on a Solex with 2SD1071, that returns the same test results, which gave me a couple of extra grey hairs
 

Skelle

New Member
Exactly one of the strange things KISS! Going to mount the original darlington into my circuit to find out what makes the Pink work on a Solex. Might be my new tester that are crap
Long story short. If 403C422 (original darlington(?)) are mounted into the constallation IT WORKS! Must be some kind of special this semiconductor...whatever it contains.
 

Skelle

New Member
Long story short. If 403C422 (original darlington(?)) are mounted into the constallation IT WORKS! Must be some kind of special this semiconductor...whatever it contains.
By the way ..tested a batch of 20pcs 2SD1071.. they return HFe in the range 16 to 22, and Uf from 916mv to 1,1V
 

debe

Active Member
This is the tests on 2 different component testers of the original Atom transistor marked A1.1.JPGA1.JPGA2.JPGA3.JPGA4.JPGA5.JPGA6.JPGA7.JPGA8.JPG
 

Attachments

Skelle

New Member
Thank you Debe, it reasures me that i’m not going mad completely. Fancy tester the second one. First one is similar to the one i found on eBay for 12$. Tried some other darlingtons, but same result both in the tester and the circuit. The Solex flywheel have 4 magnets, which makes it somewhat special. Waiting for some other transistors. Didnt expect rocketscience with a circuit that contains only 5-6 components. Very strange i must say. Also tried the ‘birdnest’ config ie no PCB involved, but it didnt change the result.
 

Skelle

New Member
Thank you Debe, it reasures me that i’m not going mad completely. Fancy tester the second one. First one is similar to the one i found on eBay for 12$. Tried some other darlingtons, but same result both in the tester and the circuit. The Solex flywheel have 4 magnets, which makes it somewhat special. Waiting for some other transistors. Didnt expect rocketscience with a circuit that contains only 5-6 components. Very strange i must say. Also tried the ‘birdnest’ config ie no PCB involved, but it didnt change the result.
Oh forgot to say, the original darlington i tested, also says ATOM - A1, and Philipnes...spelled that way. Besides a number 403C422. Also this logo that looks like 13 or 73
 

Skelle

New Member
Could there be an explanation in the Uf readings? It seems that the original Atom darlingtons have Uf above 1 Volt, where the HFe readings are moderate to low. Anyone have a good explanation to what can be learned from these readings. I mean, as we are dealing with pulses, the amp gain effect are maybe secondary to a higher Uf (voltage forward)???...just a thought
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
datasheet is here: http://www.ges.cz/sheets/2/2sd1071.pdf

there are two B-E junctions in series. That would suggest a V(b-e) of around 1.2V.
V(b-e)(Sat) is 2V from the datasheet.

Saturation values are often different when the transitor is used as a switch or amplifier. Note the curves for the saturation voltages..

The graphs also show that you need Ic to be 50 mA to show an Hfe of 40.

At Ic = 2.5 mA, Hfe might well be 8 Usually Vbe is more indicative of bad in my experience with bi-polar transistors.
 

Skelle

New Member
datasheet is here: http://www.ges.cz/sheets/2/2sd1071.pdf

there are two B-E junctions in series. That would suggest a V(b-e) of around 1.2V.
V(b-e)(Sat) is 2V from the datasheet.

Saturation values are often different when the transitor is used as a switch or amplifier. Note the curves for the saturation voltages..

The graphs also show that you need Ic to be 50 mA to show an Hfe of 40.

At Ic = 2.5 mA, Hfe might well be 8 Usually Vbe is more indicative of bad in my experience with bi-polar transistors.
My tester uses a 9volt battery, so maybe i should use a dc power supply. I’m still puzzled to why the original transistors show Uf above 1volt, and also what possible difference it would have in this config.
 

Skelle

New Member
My tester uses a 9volt battery, so maybe i should use a dc power supply. I’m still puzzled to why the original transistors show Uf above 1volt, and also what possible difference it would have in this config.
Forgot to say, used a BU910 as test...same result and same measures in the tester. One of my friends have a small supply of Darlingtons, so going to test some other models. Debe...you wrote that you tested some as well? Do you remeber the types?
 

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